Once protocol_v2 is introduced requesting a fetch or a push will need to
be handled differently depending on the protocol version. Store the
protocol version the server is speaking in 'struct git_transport_data'
and use it to determine what to do in the case of a fetch or a push.
Signed-off-by: Brandon Williams <bmwill@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>