I had hoped that the git devs could change git's handling of partial
commits to not use a false index file, but seems not.
So, this relies on some git internals to detect that case. The test suite
has a test case added to catch it if changes to git break it.
This commit was sponsored by Paul Tagliamonte.
Didn't know that this library existed!
This includes making git-annex not re-exec itself on start on windows, and
making the test suite on Windows run tests without forking.
It was possible for a interrupted sync or merge in direct mode to
leave the work tree out of sync with the last recorded commit.
This would result in the next commit seeing files missing from the work
tree, and committing their removal.
Now, a direct mode merge happens not only in a throwaway work tree, but using
a temporary index file, and without any commits or index changes
being made until the real work tree has been updated. If the merge is
interrupted, the work tree may have some updated files, but worst case a
commit will redundantly commit changes that come from the merge.
This commit was sponsored by Tony Cantor.
