presubmit: enable branch check

We're moving the hardcoded check lists out of the pre-upload script.

BUG=chromium:466264
TEST=uploading a CL w/out a branch line is rejected
BRANCH=None

Change-Id: Ie51600cdc6a635ea925d3e329cdf310e487346ea
Signed-off-by: Mike Frysinger <vapier@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/260711
Reviewed-by: Randall Spangler <rspangler@chromium.org>
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index 2e8cdb6..55b4b57 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -1,4 +1,5 @@
 [Hook Overrides]
+branch_check: true
 
 # We are using Linux style indentation with tabs
 # The indentation is checked by checkpatch not the python script