push: only ignore finish_connect() for dry-run mode

Patrick reported an issue that the exit code of git-receive-pack(1) is
ignored during atomic push with "--porcelain" flag, and added new test
cases in t5543.

Atomic push may abort the connection early and close the pipe, which
may cause an error for `finish_connect()`. Arbitrarily ignoring this
error will lead to issues. Modify it to only ignore the finish_connect()
error when both the --atomic and --dry-run flags are set.

Signed-off-by: Jiang Xin <[email protected]>

t/t5543-atomic-push.sh

@@ -280,7 +280,7 @@ test_expect_success 'atomic push reports (reject by non-ff)' '
 	test_cmp expect actual
 '
 
-test_expect_failure 'atomic push reports exit code failure' '
+test_expect_success 'atomic push reports exit code failure' '
 	write_script receive-pack-wrapper <<-\EOF &&
 	git-receive-pack "$@"
 	exit 1
@@ -296,7 +296,7 @@ test_expect_failure 'atomic push reports exit code failure' '
 	test_cmp expect err
 '
 
-test_expect_failure 'atomic push reports exit code failure with porcelain' '
+test_expect_success 'atomic push reports exit code failure with porcelain' '
 	write_script receive-pack-wrapper <<-\EOF &&
 	git-receive-pack "$@"
 	exit 1

transport.c

@@ -926,10 +926,10 @@ static int git_transport_push(struct transport *transport, struct ref *remote_re
 	close(data->fd[0]);
 	/*
 	 * Atomic push may abort the connection early and close the pipe,
-	 * which may cause an error for `finish_connect()`. Ignore this error
-	 * for atomic git-push.
+	 * which may cause an error for `finish_connect()`. We can ignore
+	 * this error when both `--atomic` and `--dry-run` flags provided.
 	 */
-	if (ret || args.atomic)
+	if (ret || (args.atomic && args.dry_run))
 		finish_connect(data->conn);
 	else
 		ret = finish_connect(data->conn);