Skip bitbucket pushes without any commits

Fixes https://sentry.io/coreos/backend-production/issues/178220183/

buildtrigger/bitbuckethandler.py

@@ -12,6 +12,7 @@ from buildtrigger.basehandler import BuildTriggerHandler
 from buildtrigger.triggerutil import (RepositoryReadException, TriggerActivationException,
                                       TriggerDeactivationException, TriggerStartException,
                                       InvalidPayloadException, TriggerProviderException,
+                                      SkipRequestException,
                                       determine_build_ref, raise_if_skipped_build,
                                       find_matching_branches)
 from util.dict_wrappers import JSONPathDict, SafeDictSetter
@@ -226,7 +227,7 @@ def get_transformed_webhook_payload(bb_payload, default_branch=None):
   payload = JSONPathDict(bb_payload)
   change = payload['push.changes[-1].new']
   if not change:
-    return None
+    raise SkipRequestException
 
   is_branch = change['type'] == 'branch'
   ref = 'refs/heads/' + change['name'] if is_branch else 'refs/tags/' + change['name']

test/test_prepare_trigger.py

@@ -511,5 +511,9 @@ class TestPrepareTrigger(unittest.TestCase):
 
     self.assertSkipped('github_webhook_knownissue', gh_webhook, lookup_user=lookup_user)
 
+
+  def test_bitbucket_webhook_known_issue(self):
+    self.assertSkipped('bitbucket_knownissue', bb_webhook)
+
 if __name__ == '__main__':
   unittest.main()

test/triggerjson/bitbucket_knownissue.json

@@ -0,0 +1,78 @@
+{
+  "push": {
+    "changes": [
+
+    ]
+  },
+  "actor": {
+    "username": "SL_jwilds",
+    "display_name": "Jim Wilds",
+    "type": "user",
+    "uuid": "{61f851e9-afbc-4bc6-bb9b-99e23c0e765a}",
+    "links": {
+      "self": {
+        "href": "https:\/\/api.bitbucket.org\/2.0\/users\/SL_jwilds"
+      },
+      "html": {
+        "href": "https:\/\/bitbucket.org\/SL_jwilds\/"
+      },
+      "avatar": {
+        "href": "https:\/\/bitbucket.org\/account\/SL_jwilds\/avatar\/32\/"
+      }
+    }
+  },
+  "repository": {
+    "website": "",
+    "scm": "git",
+    "name": "slip-api",
+    "links": {
+      "self": {
+        "href": "https:\/\/api.bitbucket.org\/2.0\/repositories\/silverlinkinc\/slip-api"
+      },
+      "html": {
+        "href": "https:\/\/bitbucket.org\/silverlinkinc\/slip-api"
+      },
+      "avatar": {
+        "href": "https:\/\/bitbucket.org\/silverlinkinc\/slip-api\/avatar\/32\/"
+      }
+    },
+    "project": {
+      "links": {
+        "self": {
+          "href": "https:\/\/api.bitbucket.org\/2.0\/teams\/silverlinkinc\/projects\/SLIP"
+        },
+        "html": {
+          "href": "https:\/\/bitbucket.org\/account\/user\/silverlinkinc\/projects\/SLIP"
+        },
+        "avatar": {
+          "href": "https:\/\/bitbucket.org\/account\/user\/silverlinkinc\/projects\/SLIP\/avatar\/32"
+        }
+      },
+      "type": "project",
+      "name": "SLIP",
+      "key": "SLIP",
+      "uuid": "{f5ba67c5-3585-453b-9412-77e4dc15be29}"
+    },
+    "full_name": "silverlinkinc\/slip-api",
+    "owner": {
+      "username": "silverlinkinc",
+      "display_name": "Silverlink",
+      "type": "team",
+      "uuid": "{9c4ce5f2-79fe-4906-9451-41fcac6bb293}",
+      "links": {
+        "self": {
+          "href": "https:\/\/api.bitbucket.org\/2.0\/teams\/silverlinkinc"
+        },
+        "html": {
+          "href": "https:\/\/bitbucket.org\/silverlinkinc\/"
+        },
+        "avatar": {
+          "href": "https:\/\/bitbucket.org\/account\/silverlinkinc\/avatar\/32\/"
+        }
+      }
+    },
+    "type": "repository",
+    "is_private": true,
+    "uuid": "{59183493-0e4a-47aa-b069-be60adce4092}"
+  }
+}

util/dict_wrappers.py

@@ -62,7 +62,12 @@ class JSONPathDict(object):
   def get(self, path, not_found_handler=None):
     """ Returns the value found at the given path. Path is a json-path expression. """
     jsonpath_expr = parse(path)
+
+    try:
       matches = jsonpath_expr.find(self._object)
+    except IndexError:
+      return None
+
     if not matches:
       return not_found_handler() if not_found_handler else None