tests/test-issue619.t

attr: vendor 22.1.0

The previous version was 5 years old, and pytype 2022.06.30 started complaining
about various uses (e.g. seeing `mercurial.thirdparty.attr._make._CountingAttr`
instead of `bytearray`).  Hopefully this helps.  Additionally, this has official
python 3.11 support.

The `attrs` package is left out, because it is simply a bunch of *.pyi stubs and
`from attr.X import *`, and that's not how they've been used up to this point.
We'd probably need to customize those anyway to
`from mercurial.thirdparty.attr import *`.

https://bz.mercurial-scm.org/619

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ hg ci -Ama
  adding a

  $ echo b > b
  $ hg branch b
  marked working directory as branch b
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -Amb
  adding b

  $ hg co -C 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Fast-forward:

  $ hg merge b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -Ammerge

Bogus fast-forward should fail:

  $ hg merge b
  abort: merging with a working directory ancestor has no effect
  [255]

Even with strange revset (issue4465)

  $ hg merge ::.
  abort: merging with a working directory ancestor has no effect
  [255]