Layman currently appends a slash to all git urls. This breaks on urls that you'd use for committing instead of just checking out. The slash should only be necessary for http:// and nothing else, so I'm attaching a patch to change this.
Created attachment 159495 [details, diff] /usr/lib/python2.5/site-packages/layman/overlays/git.py.patch
Ping!
Thanks for the patch! Fixed in layman-1.2.1. Available via portage.