Skip multi-mod check if PULL_NUMBER unset

scripts/check-multi-module.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+
+if [[ "$PULL_NUMBER" -ne "" ]]; then
+    cmd="$MYGOBIN/prchecker
+    -owner=$REPO_OWNER
+    -repo=$REPO_NAME
+    -pr=$PULL_NUMBER
+    $MODULES"
+
+
+    echo $MYGOBIN
+    echo $REPO_OWNER
+    echo $REPO_NAME
+    echo $PULL_NUMBER
+    echo $MODULES
+    eval $cmd
+else
+    echo "Multi-module check skipped. No PULL_NUMBER provided.
+
+To run this check locally set PULL_NUMBER to the PR ID from GitHub."
+fi