Added a solution by J Wyman · Feb 16 at 04:42 PM
Another workaround, until I can get the fix (aka solution) into the final product.
When this issue happens, please look in the repositories .git/ folder and check for an index.lock file. If one exists, and you're not actively running a Git command, try deleting the file. Git uses this file to indicate to any other Git processes that the repository is locked for editing. Unfortunately, if the editing process crashed or was terminated the index.lock file can get left behind and prevent any other Git process from editing the repository.
Team Explorer Hangs
Git failed with a fatal error
Git history isn't working
Git not working: Unable to start process.