http-push: Make WebDAV work with (broken?) default apache2 WebDAV module
WebDAV on Debian unstable cannot handle renames on WebDAV from file.ext to newfile (without ext) when newfile* already exists. Normally, git creates a file like 'objects/xx/sha1.token', which is renamed to 'objects/xx/sha1' when transferred completely.
Just use '_' instead of '.' so WebDAV doesn't see it as an extension change.