nodemap: make sure hooks have access to an up-to-date version
We make sure hooks can read persistent nodemap data and that they access
something up-to-date with the pending transaction.
Differential Revision: https://phab.mercurial-scm.org/D8187
Set up
$ hg init repo
$ cd repo
Try to import an empty patch
$ hg import --no-commit - <<EOF
> EOF
applying patch from stdin
abort: stdin: no diffs found
[255]
No dirstate backups are left behind
$ ls .hg/dirstate* | sort
.hg/dirstate