update vendor

Signed-off-by: Jess Frazelle <acidburn@jessfraz.com>
diff --git a/cleanup-pr-branch b/cleanup-pr-branch
index c313144..5353709 100755
--- a/cleanup-pr-branch
+++ b/cleanup-pr-branch
@@ -2,7 +2,7 @@
 set -e
 set -o pipefail
 
-if [[ ! -z "$TOKEN" ]]; then
+if [[ -n "$TOKEN" ]]; then
 	GITHUB_TOKEN=$TOKEN
 fi