Avoid a few unportable, needlessly nested "...`...".

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-request-pull.sh

@@ -24,13 +24,13 @@ headrev=`git rev-parse --verify "$head"^0` || exit
 merge_base=`git merge-base $baserev $headrev` ||
 die "fatal: No commits in common between $base and $head"
 
-url="`get_remote_url "$url"`"
-branch=`git peek-remote "$url" \
+url=$(get_remote_url "$url")
+branch=$(git peek-remote "$url" \
 	| sed -n -e "/^$headrev	refs.heads./{
 		s/^.*	refs.heads.//
 		p
 		q
-	}"`
+	}")
 if [ -z "$branch" ]; then
 	echo "warn: No branch of $url is at:" >&2
 	git log --max-count=1 --pretty='format:warn:   %h: %s' $headrev >&2