tests/test-backwards-remove.t

repoview: invalidate 'visible' filtered revisions when bookmarks change

Context: the result of computehidden, used to compute the 'visible' revisions
is cached. Its output can change when:
1) new obsolete commits are created
2) new bookmarks are created or deleted
3) new tags are created or deleted
4) the parents of the working copy change

We currently correctly invalidate the cache only in the case 1).
This patch fixes the second case (bookmarks) by invalidating the cache once
a bookmark is added or removed.

  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ ls
  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