pull-requests: properly save merge failure metadata. Before this change

when reference errors were saved the de-serialization lost some of the
attributes resulting in bad formatting of merge failure messages.

rhodecode/model/db.py

@@ -4134,6 +4134,23 b' class _PullRequestBase(BaseModel):'
         return json.dumps(self.reviewer_data)
 
     @property
+    def last_merge_metadata_parsed(self):
+        metadata = {}
+        if not self.last_merge_metadata:
+            return metadata
+
+        if hasattr(self.last_merge_metadata, 'de_coerce'):
+            for k, v in self.last_merge_metadata.de_coerce().items():
+                if k in ['target_ref', 'source_ref']:
+                    metadata[k] = Reference(v['type'], v['name'], v['commit_id'])
+                else:
+                    if hasattr(v, 'de_coerce'):
+                        metadata[k] = v.de_coerce()
+                    else:
+                        metadata[k] = v
+        return metadata
+
+    @property
     def work_in_progress(self):
         """checks if pull request is work in progress by checking the title"""
         title = self.title.upper()

rhodecode/model/pull_request.py

@@ -1600,7 +1600,7 b' class PullRequestModel(BaseModel):'
                 'source_ref': pull_request.source_ref_parts,
             }
             if pull_request.last_merge_metadata:
-                metadata.update(pull_request.last_merge_metadata)
+                metadata.update(pull_request.last_merge_metadata_parsed)
 
             if not possible and target_ref.type == 'branch':
                 # NOTE(marcink): case for mercurial multiple heads on branch