bug: autostash is lost after aborted rebase

scenario: 
- edit some tracked files; do not add them to the index
- "git config rebase.autostash true"
- "git rebase -i HEAD~3" (an autostash will be created)
- delete the entire buffer and save/exit the editor - this will abort the
  rebase

poof, the autostash is gone (it is not reapplied) -- it must be explicitly
applied again via the SHA that was printed earlier.


(please cc me; I am not subscribed to the list.)