tests/test-status-committed-and-ignored.t

rust-index: using `hg::index::Index` in `hg-cpython::dagops`

Hooking `headrevs` to the Rust index is straightforward as long as
we go the `PySharedRef` way. Direct attempts of obtaining a reference
to the inner `hg::index::Index` fail for lifetime reasons: the reference
is bound to the GIL, yet the `as_set` local variable is considered to
be static (the borrow checker clearly does not realize or care that this
set only stores `Revision` values).

In `rank()`, the chosen solution is the simplest as far as `hg-cpython` is
concerned, but it has the defect of removing an implementation
that would be easily adaptable if the core index did implement `RankedGraph`
(returning the same error as long as only `REVLOGV1` is supported), but that
would introduce a direct dependency of `hg-core` on the ``vcsgraph` crate.

#testcases dirstate-v1 dirstate-v2

#if dirstate-v2
  $ cat >> $HGRCPATH << EOF
  > [format]
  > use-dirstate-v2=1
  > [storage]
  > dirstate-v2.slow-path=allow
  > EOF
#endif

  $ rm -rf r

  $ hg init r
  $ cd r
  $ mkdir d1
  $ mkdir d2
  $ touch d1/f d2/f
  $ hg commit -Am '.'
  adding d1/f
  adding d2/f
  $ echo 'syntax:re' >> .hgignore
  $ echo '^d1$' >> .hgignore
  $ hg commit -Am "ignore d1"
  adding .hgignore

Now d1 is a directory that's both committed and ignored.
Untracked files in d2 are still shown, but ones in d1 are ignored:

  $ touch d1/g
  $ touch d2/g
  $ RAYON_NUM_THREADS=1 hg status
  ? d2/g