abuild: minor bugfix

abuild.in

@@ -741,7 +741,8 @@ builddeps() {
 
 	# find dependencies that are installed but missing in repo.
 	for i in $deps; do
-		if [ -z "$(apk search --repo "$apkcache" $i)" ]; then
+		local m=$(apk search --repo "$apkcache" $i)
+		if [ -z "$m" ]; then
 			missing="$missing $i"
 		fi
 	done