You can clone with
HTTPS or Subversion.
The executable file used for the main.rb is (when not specified otherwise) chosen by picking the first file in bin/*.rb according to the ordering returned by Dir[...], which is system-dependent. Furthermore when making this rather arbitrary choice, no warning is made in the case where there is no gemspec, and so it can take a while to track down problems.
I suggest that both cases of Dir[...].first be changed to Dir[...].sort.first and that a warning be printed in the nogemspec case as well.
I will have a pull request shortly.