diff --git a/bin/run-tc-ldc93s1_checkpoint.sh b/bin/run-tc-ldc93s1_checkpoint.sh
index 565d6986..b46d546c 100755
--- a/bin/run-tc-ldc93s1_checkpoint.sh
+++ b/bin/run-tc-ldc93s1_checkpoint.sh
@@ -5,8 +5,6 @@ set -xe
 ldc93s1_dir="./data/ldc93s1-tc"
 ldc93s1_csv="${ldc93s1_dir}/ldc93s1.csv"
 
-epoch_count=$1
-
 if [ ! -f "${ldc93s1_dir}/ldc93s1.csv" ]; then
     echo "Downloading and preprocessing LDC93S1 example data, saving in ${ldc93s1_dir}."
     python -u bin/import_ldc93s1.py ${ldc93s1_dir}
diff --git a/taskcluster/examples-base.tyml b/taskcluster/examples-base.tyml
index 8e149a9d..dc57bfb9 100644
--- a/taskcluster/examples-base.tyml
+++ b/taskcluster/examples-base.tyml
@@ -30,7 +30,7 @@ then:
     image: ${build.docker_image}
 
     env:
-      DEEPSPEECH_MODEL: "https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.14/models.tar.gz"
+      DEEPSPEECH_MODEL: "https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/models.tar.gz"
       DEEPSPEECH_AUDIO: "https://github.com/mozilla/DeepSpeech/releases/download/v0.4.1/audio-0.4.1.tar.gz"
       PIP_DEFAULT_TIMEOUT: "60"
 
diff --git a/taskcluster/tc-tests-utils.sh b/taskcluster/tc-tests-utils.sh
index 570a5cf7..2cacaa43 100755
--- a/taskcluster/tc-tests-utils.sh
+++ b/taskcluster/tc-tests-utils.sh
@@ -55,7 +55,7 @@ model_name="$(basename "${model_source}")"
 model_name_mmap="$(basename -s ".pb" "${model_source}").pbmm"
 model_source_mmap="$(dirname "${model_source}")/${model_name_mmap}"
 
-SUPPORTED_PYTHON_VERSIONS=${SUPPORTED_PYTHON_VERSIONS:-2.7.16:ucs2 2.7.16:ucs4 3.4.10:ucs4 3.5.7:ucs4 3.6.8:ucs4 3.7.3:ucs4 3.8.0:ucs4}
+SUPPORTED_PYTHON_VERSIONS=${SUPPORTED_PYTHON_VERSIONS:-2.7.16:ucs2 2.7.16:ucs4 3.5.7:ucs4 3.6.8:ucs4 3.7.3:ucs4 3.8.0:ucs4}
 SUPPORTED_NODEJS_VERSIONS=${SUPPORTED_NODEJS_VERSIONS:-4.9.1 5.12.0 6.17.1 7.10.1 8.16.0 9.11.2 10.16.0 11.15.0 12.5.0 13.0.1}
 SUPPORTED_ELECTRONJS_VERSIONS=${SUPPORTED_ELECTRONJS_VERSIONS:-1.6.18 1.7.16 1.8.8 2.0.18 3.0.16 3.1.11 4.0.3 4.1.5 4.2.5 5.0.6 6.0.11 7.0.1 7.1.2}
 
@@ -252,12 +252,12 @@ assert_correct_multi_ldc93s1()
 
 assert_correct_ldc93s1_prodmodel()
 {
-  assert_correct_inference "$1" "she had your dark suit in greasy wash water all year" "$2"
+  assert_correct_inference "$1" "she had reduce and greasy wash water all year" "$2"
 }
 
 assert_correct_ldc93s1_prodmodel_stereo_44k()
 {
-  assert_correct_inference "$1" "she had your dark suit in greasy wash water all year" "$2"
+  assert_correct_inference "$1" "she had reduce and greasy wash water all year" "$2"
 }
 
 assert_correct_warning_upsampling()
@@ -435,7 +435,7 @@ run_prod_concurrent_stream_tests()
   output2=$(echo "${output}" | tail -n 1)
 
   assert_correct_ldc93s1_prodmodel "${output1}" "${status}"
-  assert_correct_inference "${output2}" "she was ars re else are e he a" "${status}"
+  assert_correct_inference "${output2}" "we must find a new home in the stars" "${status}"
 }
 
 run_prod_inference_tests()
diff --git a/taskcluster/tc-train-tests.sh b/taskcluster/tc-train-tests.sh
index a08624b4..a782fa18 100644
--- a/taskcluster/tc-train-tests.sh
+++ b/taskcluster/tc-train-tests.sh
@@ -58,8 +58,8 @@ LD_LIBRARY_PATH=${PY37_LDPATH}:$LD_LIBRARY_PATH pip install --verbose --only-bin
 
 pushd ${HOME}/DeepSpeech/ds/
     # Run twice to test preprocessed features
-    time ./bin/run-tc-ldc93s1_new.sh 199
-    time ./bin/run-tc-ldc93s1_new.sh 200
+    time ./bin/run-tc-ldc93s1_new.sh 219
+    time ./bin/run-tc-ldc93s1_new.sh 1
     time ./bin/run-tc-ldc93s1_tflite.sh
 popd
 
@@ -75,7 +75,7 @@ if [ ! -z "${CONVERT_GRAPHDEF_MEMMAPPED}" ]; then
 fi;
 
 pushd ${HOME}/DeepSpeech/ds/
-    time ./bin/run-tc-ldc93s1_checkpoint.sh 200
+    time ./bin/run-tc-ldc93s1_checkpoint.sh
 popd
 
 deactivate
diff --git a/taskcluster/test-armbian-opt-base.tyml b/taskcluster/test-armbian-opt-base.tyml
index 9e3850de..76733c02 100644
--- a/taskcluster/test-armbian-opt-base.tyml
+++ b/taskcluster/test-armbian-opt-base.tyml
@@ -36,8 +36,8 @@ then:
       in:
         DEEPSPEECH_ARTIFACTS_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${linux_arm64_build}/artifacts/public
         DEEPSPEECH_TEST_MODEL: https://community-tc.services.mozilla.com/api/queue/v1/task/${training}/artifacts/public/output_graph.pb
-        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pb
-        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pbmm
+        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pb
+        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pbmm
         PIP_DEFAULT_TIMEOUT: "60"
         PIP_EXTRA_INDEX_URL: "https://lissyx.github.io/deepspeech-python-wheels/"
         EXTRA_PYTHON_CONFIGURE_OPTS: "" # Required by Debian Buster
diff --git a/taskcluster/test-darwin-opt-base.tyml b/taskcluster/test-darwin-opt-base.tyml
index e2463104..6206a22e 100644
--- a/taskcluster/test-darwin-opt-base.tyml
+++ b/taskcluster/test-darwin-opt-base.tyml
@@ -41,8 +41,8 @@ then:
         DEEPSPEECH_ARTIFACTS_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${darwin_amd64_build}/artifacts/public
         DEEPSPEECH_ARTIFACTS_TFLITE_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${darwin_amd64_tflite}/artifacts/public
         DEEPSPEECH_TEST_MODEL: https://community-tc.services.mozilla.com/api/queue/v1/task/${training}/artifacts/public/output_graph.pb
-        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pb
-        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pbmm
+        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pb
+        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pbmm
         EXPECTED_TENSORFLOW_VERSION: "${build.tensorflow_git_desc}"
 
     command:
diff --git a/taskcluster/test-linux-opt-base.tyml b/taskcluster/test-linux-opt-base.tyml
index 63b0d6b7..f3de6fc9 100644
--- a/taskcluster/test-linux-opt-base.tyml
+++ b/taskcluster/test-linux-opt-base.tyml
@@ -41,8 +41,8 @@ then:
         DEEPSPEECH_ARTIFACTS_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${linux_amd64_build}/artifacts/public
         DEEPSPEECH_ARTIFACTS_TFLITE_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${linux_amd64_tflite}/artifacts/public
         DEEPSPEECH_TEST_MODEL: https://community-tc.services.mozilla.com/api/queue/v1/task/${training}/artifacts/public/output_graph.pb
-        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pb
-        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pbmm
+        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pb
+        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pbmm
         DECODER_ARTIFACTS_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${linux_amd64_ctc}/artifacts/public
         PIP_DEFAULT_TIMEOUT: "60"
         EXPECTED_TENSORFLOW_VERSION: "${build.tensorflow_git_desc}"
diff --git a/taskcluster/test-python_34m-darwin-amd64-opt.yml b/taskcluster/test-python_34m-darwin-amd64-opt.yml
deleted file mode 100644
index df79734f..00000000
--- a/taskcluster/test-python_34m-darwin-amd64-opt.yml
+++ /dev/null
@@ -1,13 +0,0 @@
-build:
-  template_file: test-darwin-opt-base.tyml
-  dependencies:
-    - "darwin-amd64-cpu-opt"
-    - "test-training_upstream-linux-amd64-py36m-opt"
-  system_setup:
-    >
-      ${python.brew.setup} && ${python.brew.env}
-  args:
-    tests_cmdline: "$TASKCLUSTER_TASK_DIR/DeepSpeech/ds/taskcluster/tc-python-tests.sh 3.4.8:m"
-  metadata:
-    name: "DeepSpeech OSX AMD64 CPU Python v3.4 tests"
-    description: "Testing DeepSpeech for OSX/AMD64 on Python v3.4, CPU only, optimized version"
diff --git a/taskcluster/test-python_34m-linux-amd64-opt.yml b/taskcluster/test-python_34m-linux-amd64-opt.yml
deleted file mode 100644
index c86f0509..00000000
--- a/taskcluster/test-python_34m-linux-amd64-opt.yml
+++ /dev/null
@@ -1,13 +0,0 @@
-build:
-  template_file: test-linux-opt-base.tyml
-  dependencies:
-    - "linux-amd64-cpu-opt"
-    - "test-training_upstream-linux-amd64-py36m-opt"
-  system_setup:
-    >
-      apt-get -qq -y install ${python.packages_trusty.apt}
-  args:
-    tests_cmdline: "${system.homedir.linux}/DeepSpeech/ds/taskcluster/tc-python-tests.sh 3.4.8:m"
-  metadata:
-    name: "DeepSpeech Linux AMD64 CPU Python v3.4 tests"
-    description: "Testing DeepSpeech for Linux/AMD64 on Python v3.4, CPU only, optimized version"
diff --git a/taskcluster/test-python_34m-linux-amd64-prod_pbmodel-opt.yml b/taskcluster/test-python_34m-linux-amd64-prod_pbmodel-opt.yml
deleted file mode 100644
index 00caa8a7..00000000
--- a/taskcluster/test-python_34m-linux-amd64-prod_pbmodel-opt.yml
+++ /dev/null
@@ -1,12 +0,0 @@
-build:
-  template_file: test-linux-opt-base.tyml
-  dependencies:
-    - "linux-amd64-cpu-opt"
-  system_setup:
-    >
-      apt-get -qq -y install ${python.packages_trusty.apt}
-  args:
-    tests_cmdline: "${system.homedir.linux}/DeepSpeech/ds/taskcluster/tc-python-tests-prod.sh 3.4.8:m"
-  metadata:
-    name: "DeepSpeech Linux AMD64 CPU Python v3.4 prod tests"
-    description: "Testing DeepSpeech for Linux/AMD64 on Python v3.4 on prod model, CPU only, optimized version"
diff --git a/taskcluster/test-raspbian-opt-base.tyml b/taskcluster/test-raspbian-opt-base.tyml
index f47b020d..faf511a8 100644
--- a/taskcluster/test-raspbian-opt-base.tyml
+++ b/taskcluster/test-raspbian-opt-base.tyml
@@ -36,8 +36,8 @@ then:
       in:
         DEEPSPEECH_ARTIFACTS_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${linux_rpi3_build}/artifacts/public
         DEEPSPEECH_TEST_MODEL: https://community-tc.services.mozilla.com/api/queue/v1/task/${training}/artifacts/public/output_graph.pb
-        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pb
-        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pbmm
+        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pb
+        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pbmm
         PIP_DEFAULT_TIMEOUT: "60"
         PIP_EXTRA_INDEX_URL: "https://www.piwheels.org/simple"
         EXTRA_PYTHON_CONFIGURE_OPTS: "" # Required by Raspbian Buster / PiWheels
diff --git a/taskcluster/test-win-opt-base.tyml b/taskcluster/test-win-opt-base.tyml
index 82aeb0b6..3ff211e6 100644
--- a/taskcluster/test-win-opt-base.tyml
+++ b/taskcluster/test-win-opt-base.tyml
@@ -43,8 +43,8 @@ then:
         DEEPSPEECH_ARTIFACTS_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${win_amd64_build}/artifacts/public
         DEEPSPEECH_ARTIFACTS_TFLITE_ROOT: https://community-tc.services.mozilla.com/api/queue/v1/task/${win_amd64_tflite}/artifacts/public
         DEEPSPEECH_TEST_MODEL: https://community-tc.services.mozilla.com/api/queue/v1/task/${training}/artifacts/public/output_graph.pb
-        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pb
-        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.11/output_graph.pbmm
+        DEEPSPEECH_PROD_MODEL: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pb
+        DEEPSPEECH_PROD_MODEL_MMAP: https://github.com/reuben/DeepSpeech/releases/download/v0.6.0-alpha.15/output_graph.pbmm
         EXPECTED_TENSORFLOW_VERSION: "${build.tensorflow_git_desc}"
         TC_MSYS_VERSION: 'MSYS_NT-6.3'
         MSYS: 'winsymlinks:nativestrict'