git-fetch: Fix single_force in append_fetch_head

This fixes the single force (+) when fetched with fetch_per_ref.

Also use $LF as separator because IFS is $LF.

Signed-off-by: Santi Béjar <sbejar@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git-fetch.sh

@@ -110,8 +110,8 @@ ls_remote_result=$(git ls-remote $exec "$remote") ||
 
 append_fetch_head () {
 	flags=
-	test -n "$verbose" && flags="$flags -v"
-	test -n "$force" && flags="$flags -f"
+	test -n "$verbose" && flags="$flags$LF-v"
+	test -n "$force$single_force" && flags="$flags$LF-f"
 	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION" \
 		git-fetch--tool $flags append-fetch-head "$@"
 }