tests/test-backwards-remove.t

commit: force create a new filenode if it was set in mergestate by merge

For reasons mentioned in previous commits, we will like to forcefully create a
new filenode sometimes.

Combination of this patch and previous one, we fixed a case in
`test-merge-combination.t`.

This does not yet results in conflict where it should, I need to investigate
more about what's happening as it should be a change-delete conflict now.

Differential Revision: https://phab.mercurial-scm.org/D8989

  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ ls -A
  .hg
  a
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

B should disappear

  $ ls -A
  .hg
  a