tests/test-revert-unknown.t

obsolete: always return frozensets from obsolete.getrevs()

getrevs function already returns an empty frozenset when there is no obsstore,
but let's make sure to return a frozenset in any case. This makes it possible
to use the result of this function as a dict key or provide it to hash()
built-in function without any conversions.

Differential Revision: https://phab.mercurial-scm.org/D12156

  $ hg init
  $ touch unknown

  $ touch a
  $ hg add a
  $ hg ci -m "1"

  $ touch b
  $ hg add b
  $ hg ci -m "2"

Should show unknown

  $ hg status
  ? unknown
  $ hg revert -r 0 --all
  removing b

Should show unknown and b removed

  $ hg status
  R b
  ? unknown

Should show a and unknown

  $ ls -A
  .hg
  a
  unknown