Support pulling out the original base commit

src/api/pull_request.rs

@@ -71,6 +71,24 @@ impl PullRequest {
         &self.base.gitref
     }
 
+    /// The base commit of the branch is stored in the pull request for later.
+    /// This digs it out if possible.
+    /// There is a timestamp included.
+    pub fn base_commit(&self) -> Option<(&str, u64)> {
+        let regex = Regex::new("git-stack-base-commit:([a-z0-9]+)@([0-9]+)").unwrap();
+        self.body
+            .as_ref()
+            .map(|body| {
+                regex.captures(&body).map(|re_match| {
+                    (
+                        re_match.get(1).unwrap().as_str(),
+                        re_match[2].parse().unwrap(),
+                    )
+                })
+            })
+            .flatten()
+    }
+
     /// Stored version of the base branch in the pull request body.
     /// Needed for when the original branch is merged and so it vanishes.
     pub fn base_branch_orig(&self) -> Option<&str> {