Although Net::Domain::domainname attempts to be very thorough, the
host's configuration can still refuse to give a FQDN. Check to see if
what we receive contains a dot as a basic sanity check.
Since the same condition is used twice and getting complex, let's move
it to a new function.
Signed-off-by: Brian Gernhardt <brian@gernhardtsoftware.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>