pr: Catch errors if target or source reference are missing during commit update. #3950

rhodecode/model/pull_request.py

@@ -526,7 +526,14 b' class PullRequestModel(BaseModel):'
                 old=pull_request, new=None, changes=None)
 
         source_repo = pull_request.source_repo.scm_instance()
+        try:
         source_commit = source_repo.get_commit(commit_id=source_ref_name)
+        except CommitDoesNotExistError:
+            return UpdateResponse(
+                success=False,
+                reason=UpdateFailureReason.MISSING_SOURCE_REF,
+                old=pull_request, new=None, changes=None)
+
         if source_ref_id == source_commit.raw_id:
             log.debug("Nothing changed in pull request %s", pull_request)
             return UpdateResponse(
@@ -543,10 +550,16 b' class PullRequestModel(BaseModel):'
         target_ref_id = pull_request.target_ref_parts.commit_id
         target_repo = pull_request.target_repo.scm_instance()
 
+        try:
         if target_ref_type in ('tag', 'branch', 'book'):
             target_commit = target_repo.get_commit(target_ref_name)
         else:
             target_commit = target_repo.get_commit(target_ref_id)
+        except CommitDoesNotExistError:
+            return UpdateResponse(
+                success=False,
+                reason=UpdateFailureReason.MISSING_TARGET_REF,
+                old=pull_request, new=None, changes=None)
 
         # re-compute commit ids
         old_commit_ids = set(pull_request.revisions)