Git for Windows 1.x was retired on August 18th, 2015, superseded by Git for Windows 2.x. The source code of Git for Windows 2.x is maintained in the git-for-windows org, a friendly fork of Git that aims to vet Windows-specific patches until they are submitted upstream.
This is the source code of Git for Windows 1.x, forked from Git.
If you encounter problems, you are highly encouraged to switch to Git for Windows 2.x. Pull Requests for critical issues in Git for Windows 1.x will of course accepted, though.