Fix _CheckAddedDepsHaveTargetApprovals for the case where no owner has been specified.

[email protected]
BUG=none

Review URL: https://codereview.chromium.org/15491008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@201426 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 3418265..1253c4a0 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -774,7 +774,9 @@
 
   owner_email = owner_email or input_api.change.author_email
 
-  reviewers_plus_owner = set([owner_email]).union(reviewers)
+  reviewers_plus_owner = reviewers
+  if owner_email:
+    reviewers_plus_owner = set([owner_email]).union(reviewers)
   missing_files = owners_db.files_not_covered_by(virtual_depended_on_files,
                                                  reviewers_plus_owner)
   unapproved_dependencies = ["'+%s'," % path[:-len('/DEPS')]