Merge branch 'jc/fetch' into next

* jc/fetch:
  fetch: exit non-zero when fast-forward check fails.

git-fetch.sh

@@ -185,6 +185,7 @@ fast_forward_local () {
 			;;
 		*)
 			echo >&2 "  not updating."
+			exit 1
 			;;
 		esac
 	    }