download_https_uri_to_file(): do not leak fd upon failure

When the `git-remote-https` command fails, we do not want to leak
`child_out`.

Pointed out by Coverity.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bundle-uri.c

@@ -378,7 +378,7 @@ cleanup:
 	if (child_in)
 		fclose(child_in);
 	if (finish_command(&cp))
-		return 1;
+		result = 1;
 	if (child_out)
 		fclose(child_out);
 	return result;