Bash exit status for failures should be positive, not negative.

Test: TH
Change-Id: Idb0e0c23079e8ea99f89266e851f3e0206cc46bf
diff --git a/scripts/run_presubmits.sh b/scripts/run_presubmits.sh
index f999df0..d70d9c7 100755
--- a/scripts/run_presubmits.sh
+++ b/scripts/run_presubmits.sh
@@ -4,7 +4,7 @@
 
 if [[ ! -d "build/bazel/ci" ]]; then
   echo "Please run this script from TOP".
-  exit -1
+  exit 1
 fi
 
 echo "Running presubmit scripts..."