transport-helper: fix sync issue on crashes
When a remote helper crashes while pushing we should revert back to the
state before the push, however, it's possible that `git fast-export`
already finished its job, and therefore has exported the marks already.
This creates a synchronization problem because from that moment on
`git fast-{import,export}` will have marks that the remote helper is not
aware of and all further commands fail (if those marks are referenced).
The fix is to tell `git fast-export` to export to a temporary file, and
only after the remote helper has finishes successfully, move to the
final destination.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
projects / git / commit
