Don't create Github repositories if there's no releases to import.

[schwern]

For example, the "test" distribution contains both JAMSHAID/test-1.1.tar.gz and YEWEI/test.tgz which are skipped. The importer makes a "test" repository on Github before checking to see if there's anything to import. The result is an empty "test" repository on Github which blocks the legit "Test" distribution from being imported.

The chain of events is as follows...

• import_releases calls releases_to_import
• Gitpan::Dist needs a Gitpan::Git instance to check what's already been imported
• Since the Git repo does not exist, Gitpan::Dist needs a Gitpan::Github instance to make sure a repo exists to clone from
• Gitpan::Dist has Gitpan::Github create a repository
• Gitpan::Dist has Gitpan::Git clone from the repository
• Gitpan::Git reports no releases have been imported
• releases_to_import skips all releases and reports no releases to import
• import_releases returns

While convenient, that Gitpan::Dist will create repositories just to get a Git instance has been a problem in other places and has proven wasteful.

One solution would be to change releases_to_import to check if a Git or Github repository already exists. If not, don't make one.

Another, more involved, would be to create a Gitpan::Git derivative which operates when there is no git repository. Some methods, such as releases, simply return false. Others, such as add_all, would create the repository on demand.

A third, and least magical, solution would be to add an explicit repository initialization step to Gitpan::Dist. Gitpan::Dist is probably over architected.

[schwern]

I went ahead and rearchitected Gitpan::Dist. Gitpan::Repo now handles the coordination of Gitpan::Github and Gitpan::Git and does so lazily, it won't make a Github repository until its time to push. It handles making sure Git and Github are in sync. Gitpan::Dist will be just about feeding releases to Gitpan::Repo.