Remove source branches is batch jobs if necessary

In batch jobs source branch deletion can be bypassed, despite the
setting being enabled in the original merge request. This change will
check if the source branch should be deleted and make the appropriate
API call to delete if so

Author: sdclarke

marge/batch_job.py

@@ -1,6 +1,7 @@
 # pylint: disable=too-many-branches,too-many-statements,arguments-differ
 import logging as log
 from time import sleep
+from requests.utils import quote
 
 from . import git
 from . import gitlab
@@ -9,6 +10,8 @@
 from .merge_request import MergeRequest
 from .pipeline import Pipeline
 
+DELETE = gitlab.DELETE
+
 
 class CannotBatch(Exception):
     pass
@@ -195,6 +198,16 @@ def accept_mr(
         for pipeline in pipelines:
             pipeline.cancel()
 
+        if merge_request.force_remove_source_branch:
+            self._api.call(
+                DELETE(
+                    'projects/{}/repository/branches/{}'.format(
+                        merge_request.source_project_id,
+                        quote(merge_request.source_branch, safe='')
+                    )
+                )
+            )
+
         return final_sha
 
     def execute(self):