tests/test-empty-manifest-index.t

commit: remove special handling of IOError (actually dead code)

In the past, IOError was used to mark a file as removed. The differentiation
between OSError and IOError in this place was introduced in e553a425751d, to
avoid that “normal” OSErrors / IOErrors accidentally mark files as removed.
This weird internal API was removed in 650b5b6e75ed. It seems like that
changeset should have removed the differentiation, at least I don’t see any
reason for keeping it.

On Python 3, OSError and IOError are aliased. Therefore the removed code was
actually dead.

Test null revisions (node 0000000000000000000000000000000000000000, aka rev -1)
in various circumstances.

Make an empty repo:

  $ hg init a
  $ cd a

  $ hg files -r 0000000000000000000000000000000000000000
  [1]
  $ hg files -r .
  [1]

Add an empty commit (this makes the changelog refer to a null manifest node):


  $ hg commit -m "init" --config ui.allowemptycommit=true

  $ hg files -r .
  [1]

Strip that empty commit (this makes the changelog file empty, as opposed to missing):

  $ hg --config 'extensions.strip=' strip . > /dev/null

  $ hg files -r .
  [1]