gitlab-ci-cd/drupal#57 Allow the merge script to exit gracefully if no changes are available

bin/merge

@@ -29,10 +29,13 @@ fi
 
 git fetch
 rm /tmp/glab.log >/dev/null 2>&1 || true
-glab mr create --fill --yes --source-branch ${SOURCEBRANCH} --target-branch ${TARGETBRANCH} --title "$TITLE" > /tmp/glab.log
+glab mr create --fill --yes --source-branch ${SOURCEBRANCH} --target-branch ${TARGETBRANCH} --title "$TITLE" > /tmp/glab.log 2>&1
+EC=0
+grep "could not find any commits" /tmp/glab.log || EC=$?
+if [[ $EC -eq 0 ]]; then echo "No changes available."; exit 0; fi
 EC=0
 grep "Failed to create merge request." /tmp/glab.log || EC=$?
-if [[ $EC -eq 0 ]]; then glab mr create --recover > /tmp/glab.log; fi
+if [[ $EC -eq 0 ]]; then glab mr create --recover > /tmp/glab.log 2>&1; fi
 EC=0
 grep "Failed to create merge request." /tmp/glab.log || EC=$?
 if [[ $EC -eq 0 ]]; then exit 1; fi