onnects to given service. Standard input and standard output
of helper are connected to specified service (git prefix is
included in service name so e.g. fetching uses <em>git-upload-pack</em>
as service) on remote side. Valid replies to this command are
empty line (connection established), <em>fallback</em> (no smart
transport support, fall back to dumb transports) and just
exiting with error message printed (can&#8217;t connect, don&#8217;t
bother trying to fall back). After line feed terminating the
posi