Add relative path support.

verification/project_base.py

Index: verification/project_base.py
diff --git a/verification/project_base.py b/verification/project_base.py
index 34ff5e29927453f204876d7b8fb7fd8eab6794e6..5863ac33acb10bbf40cdd6072b932bc68db04382 100644
--- a/verification/project_base.py
+++ b/verification/project_base.py
@@ -5,8 +5,12 @@
 """Ignores issues not using the right project base url regex."""
 
 import logging
+import os
 import re
 
+import find_depot_tools  # pylint: disable=W0611
+import breakpad
+
 from verification import base
 
 
@@ -19,10 +23,19 @@ class ProjectBaseUrlVerifier(base.Verifier):
     self.project_bases = project_bases
 
   def verify(self, pending, revision):
-    if not any(re.match(r, pending.base_url) for r in self.project_bases):
+    matches = filter(
+        None, (re.match(r, pending.base_url) for r in self.project_bases))
+    if not matches:
       logging.info('%s not in whitelist' % pending.base_url)
       state = base.IGNORED
     else:
+      if len(matches) != 1:
+        breakpad.SendStack(
+            Exception('pending.base_url triggered multiple matches'), '')
+      match = matches[0]
+      if match.lastindex:
+        pending.relpath = match.group(match.lastindex).lstrip('/').replace(
+            '/', os.sep)
       state = base.SUCCEEDED
     pending.verifications[self.name] = base.SimpleStatus(state)