When we have a URI that contains an empty path component (that is
it only contains a "/") we want to fall back to the host as
humanish name.
This change is according to the behavior of upstream git, which
falls back on the hostname when guessing directory names for
newly cloned repositories (see [1] for the discussion).
[1] http://article.gmane.org/gmane.comp.version-control.git/274669
Change-Id: I44400c6ab72a2722d2155d53d63671bd867d6c44
Signed-off-by: Patrick Steinhardt <ps@pks.im>