test for adding crazy branches

as found by dansmith's clever hack, if devstack lands a crazy
branch name in stackrc, we'd break the devstack gate. While it's
doubtful anyone would do this, add a basic sanity check.

Change-Id: Ib3b1881ed4fd520a1828ed073a7c8353e6f0a839
diff --git a/run_tests.sh b/run_tests.sh
index a0bfbee..685b203 100755
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -27,3 +27,16 @@
 echo "Running bash8..."
 
 ./tools/bash8.py -v $FILES
+
+
+# Test that no one is trying to land crazy refs as branches
+
+echo "Ensuring we don't have crazy refs"
+
+REFS=`grep BRANCH stackrc | grep -v -- '-master'`
+rc=$?
+if [[ $rc -eq 0 ]]; then
+    echo "Branch defaults must be master. Found:"
+    echo $REFS
+    exit 1
+fi