logging: log the original error when a merge failure occurs

rhodecode/lib/vcs/backends/git/repository.py

@@ -853,7 +853,8 b' class GitRepository(BaseRepository):'
         shadow_repo._checkout(pr_branch, create=True)
         try:
             shadow_repo._local_fetch(source_repo.path, source_ref.name)
-        except RepositoryError:
+        except RepositoryError as e:
+            log.exception('Failure when doing local fetch on git shadow repo')
             return MergeResponse(
                 False, False, None, MergeFailureReason.MISSING_COMMIT)
 
@@ -863,7 +864,8 b' class GitRepository(BaseRepository):'
             shadow_repo._local_merge(merge_message, merger_name, merger_email,
                                      [source_ref.commit_id])
             merge_possible = True
-        except RepositoryError:
+        except RepositoryError as e:
+            log.exception('Failure when doing local merge on git shadow repo')
             merge_possible = False
             merge_failure_reason = MergeFailureReason.MERGE_FAILED
 
@@ -877,7 +879,9 b' class GitRepository(BaseRepository):'
                 # cannot retrieve the merge commit.
                 shadow_repo = GitRepository(shadow_repository_path)
                 merge_commit_id = shadow_repo.branches[pr_branch]
-            except RepositoryError:
+            except RepositoryError as e:
+                log.exception(
+                    'Failure when doing local push on git shadow repo')
                 merge_succeeded = False
                 merge_failure_reason = MergeFailureReason.PUSH_FAILED
         else:

rhodecode/lib/vcs/backends/hg/repository.py

@@ -669,7 +669,8 b' class MercurialRepository(BaseRepository'
         try:
             source_repo._validate_pull_reference(source_ref)
             shadow_repo._local_pull(source_repo.path, source_ref)
-        except CommitDoesNotExistError:
+        except CommitDoesNotExistError as e:
+            log.exception('Failure when doing local pull on hg shadow repo')
             return MergeResponse(
                 False, False, None, MergeFailureReason.MISSING_COMMIT)
 
@@ -681,7 +682,8 b' class MercurialRepository(BaseRepository'
                 target_ref, merge_message, merger_name, merger_email,
                 source_ref)
             merge_possible = True
-        except RepositoryError:
+        except RepositoryError as e:
+            log.exception('Failure when doing local merge on hg shadow repo')
             merge_possible = False
             merge_failure_reason = MergeFailureReason.MERGE_FAILED
 
@@ -705,7 +707,9 b' class MercurialRepository(BaseRepository'
                         merge_commit_id, self.path, push_branches=True,
                         enable_hooks=True)
                     merge_succeeded = True
-                except RepositoryError:
+                except RepositoryError as e:
+                    log.exception(
+                        'Failure when doing local push on hg shadow repo')
                     merge_succeeded = False
                     merge_failure_reason = MergeFailureReason.PUSH_FAILED
             else: