tests/test-empty.t

automation: always use latest Windows AMI

The old AMI isn't available any more.

We seem to run into this problem every few months. Amazon (or
Microsoft) appears to be removing the old AMIs when they are
superseded or something. Let's give up on tracking known images
and switch the image selection logic to use the latest published
image.

Differential Revision: https://phab.mercurial-scm.org/D8465

Create an empty repo:

  $ hg init a
  $ cd a

Try some commands:

  $ hg log
  $ hg grep wah
  [1]
  $ hg manifest
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 0 changesets with 0 changes to 0 files

Check the basic files created:

  $ ls .hg
  00changelog.i
  cache
  requires
  store
  wcache

Should be empty:

  $ ls .hg/store

Poke at a clone:

  $ cd ..
  $ hg clone a b
  updating to branch default
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd b
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 0 changesets with 0 changes to 0 files
  $ ls .hg
  00changelog.i
  hgrc
  requires
  store

Should be empty:

  $ ls .hg/store

  $ cd ..