[IMP] forwardport: unweird singleton conflicting commits

When creating the conflicting commit of a single commit PR, reuse the
original commit's meta-information so the developer / fixer can more
easily update it in-place.

Closes #204

forwardport/models/project.py

@@ -605,8 +605,7 @@ More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port
             working_copy.checkout('-bsquashed', root_branch)
             root_commits = root.commits()
 
-            # squash to a single commit: reset to the first parent of the pr's
-            # first commit
+            # squash to a single commit
             working_copy.reset('--soft', root_commits[0]['parents'][0]['sha'])
             working_copy.commit(a=True, message="temp")
             squashed = working_copy.stdout().rev_parse('HEAD').stdout.strip().decode()
@@ -616,9 +615,15 @@ More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port
             # cherry-pick the squashed commit
             working_copy.with_params('merge.renamelimit=0').with_config(check=False).cherry_pick(squashed)
 
-            working_copy.commit(
-                a=True, allow_empty=True,
-                message="""Cherry pick of %s failed
+            # if there was a single commit, reuse its message when committing
+            # the conflict
+            # TODO: still add conflict information to this?
+            if len(root_commits) == 1:
+                working_copy.commit(all=True, allow_empty=True, reuse_message=root_commits[0]['sha'])
+            else:
+                working_copy.commit(
+                    all=True, allow_empty=True,
+                    message="""Cherry pick of %s failed
 
 stdout:
 %s