Ignore repositories that are not yet initialized (no commits) 

This patch makes a repository with no commit ignored (considered as not a git repo).

This is a quick fix preventing newly-created repos to make the whole list fail in gitlist (even if there is other repos):

<ref>
Oops! An exception has been thrown during the rendering of a template ("Parameter "branch" for route "rss" must match "(?!/|.*([/.]\.|//|@\{|\\))[^\040\177 ~^:?*\[]+(?<!\.lock|[/.])" ("" given) to generate a corresponding URL.") in "index.twig" at line 13. 
</ref>

A more suitable fix would be to display something specific for empty repos.