tests/test-dirstate-race2.t

dirstate-tree: Add a dirstate-v1-tree variant of some tests

The `dirstate-v1` variant has the previous behavior.

`dirstate-v1-tree` uses the same format on disk, but uses the new
`DirstateMap` with a tree data structure and the new `status` algorithm.
These were untested so far.

Differential Revision: https://phab.mercurial-scm.org/D10698

#testcases dirstate-v1 dirstate-v1-tree

#if dirstate-v1-tree
#require rust
  $ echo '[experimental]' >> $HGRCPATH
  $ echo 'dirstate-tree.in-memory=1' >> $HGRCPATH
#endif

Checking the size/permissions/file-type of files stored in the
dirstate after an update where the files are changed concurrently
outside of hg's control.

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg commit -qAm _
  $ echo aa > a
  $ hg commit -m _

  $ hg debugdirstate --no-dates
  n 644          3 (set  |unset)               a (re)

  $ cat >> $TESTTMP/dirstaterace.py << EOF
  > from mercurial import (
  >     extensions,
  >     merge,
  > )
  > def extsetup(ui):
  >     extensions.wrapfunction(merge, 'applyupdates', wrap)
  > def wrap(orig, *args, **kwargs):
  >     res = orig(*args, **kwargs)
  >     with open("a", "w"):
  >         pass # just truncate the file
  >     return res
  > EOF

Do an update where file 'a' is changed between hg writing it to disk
and hg writing the dirstate. The dirstate is correct nonetheless, and
so hg status correctly shows a as clean.

  $ hg up -r 0 --config extensions.race=$TESTTMP/dirstaterace.py
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg debugdirstate --no-dates
  n 644          2 (set  |unset)               a (re)
  $ echo a > a; hg status; hg diff