send-pack: fix inconsistent porcelain output

send-pack: fix inconsistent porcelain output

The porcelain output of a failed `git-push` command is inconsistent for
different protocols.  For example, the following `git-push` command
may fail due to the failure of the `pre-receive` hook.

    git push --porcelain origin HEAD:refs/heads/master

For SSH protocol, the porcelain output does not end with a "Done"
message:

	To <URL/of/upstream.git>
	!  HEAD:refs/heads/master  [remote rejected] (pre-receive hook declined)

While for HTTP protocol, the porcelain output does end with a "Done"
message:

	To <URL/of/upstream.git>
	!  HEAD:refs/heads/master  [remote rejected] (pre-receive hook declined)
	Done

The following code at the end of function `send_pack()` indicates that
`send_pack()` should not return an error if some references are rejected
in porcelain mode.

    int send_pack(...)
        ... ...

        if (args->porcelain)
            return 0;

        for (ref = remote_refs; ref; ref = ref->next) {
            switch (ref->status) {
            case REF_STATUS_NONE:
            case REF_STATUS_UPTODATE:
            case REF_STATUS_OK:
                break;
            default:
                return -1;
            }
        }
        return 0;
    }

So if atomic push failed, must check the porcelain mode before return
an error.  And `receive_status()` should not return an error for a
failed updated reference, because `send_pack()` will check them instead.

Signed-off-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>