tests/test-empty.t

rebase: delete obsolete internal "keepopen" option

The option was apparently introduced for use by the "pbranch"
extension, see f2558a8228be (rebase: add option to not commit after a
collapsing, 2010-02-07). However, it doesn't seem like it was ever
used by that extension (according to `hg grep` in a clone of
https://bitbucket.org/parren/hg-pbranch/), so let's delete it.

Differential Revision: https://phab.mercurial-scm.org/D2708

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
  0 files, 0 changesets, 0 total revisions

Check the basic files created:

  $ ls .hg
  00changelog.i
  requires
  store

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
  0 files, 0 changesets, 0 total revisions
  $ ls .hg
  00changelog.i
  hgrc
  requires
  store

Should be empty:

  $ ls .hg/store

  $ cd ..