send-pack/transport-helper: avoid mentioning a particular branch

send-pack/transport-helper: avoid mentioning a particular branch

When trying to push all matching branches, but none match, we offer a
message suggesting to push the `master` branch.

However, we want to step away from making that branch any more special
than any other branch, so let's reword that message to mention no branch
in particular.

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