Improve existing git helper scripts

buildroot/share/git/mfinfo

@@ -37,4 +37,8 @@ case "$#" in
   * ) echo "Usage: `basename $0` [branch]" 1>&2 ; exit 1 ;;
 esac
 
+if [[ $BRANCH == "(no" ]]; then
+  echo "Git is busy with merge, rebase, etc." 1>&2 ; exit 1
+fi
+
 echo "$ORG $FORK $REPO $TARG $BRANCH"