Only recreate signatures if needed

update-keys

@@ -56,8 +56,10 @@ done < packager-keyids
 cat master/*.asc packager/*.asc > archlinux.gpg
 
 for s in archlinux{.gpg,-trusted,-revoked}; do
-	rm -f ${s}.sig
-	gpg --detach-sign --use-agent ${s}
+	if ! ${GPG} --verify ${s}.sig; then
+		rm -f ${s}.sig
+		gpg --detach-sign --use-agent ${s}
+	fi
 done
 
 popd >/dev/null