Cannot push anything via export transport helper after push fails.

[Andrey Borzenkov <arvidjaar@gmail.com>]

I noticed that using git-remote-bzr, but as far as I can tell this is
generic for all transport helpers using fast-export.



What happened was "git push" failed due to merge conflict. So far so
good - but from now on git assumes everything is up to date.

bor@opensuse:/tmp/test/git> git push origin master
To bzr::bzr+ssh://bor@localhost/tmp/test/bzr
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'bzr::bzr+ssh://bor@localhost/tmp/test/bzr'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Merge the remote changes (e.g. 'git pull')
hint: before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
bor@opensuse:/tmp/test/git> git push origin master
Everything up-to-date
bor@opensuse:/tmp/test/git> 

The problem seems to be that git fast-export updates marks
unconditionally, whether export actually applied or not. So next time
it assumes everything is already exported and does nothing.

Is it expected behavior?

TIA

-andrey