tests/test-revert-unknown.t

reachableroots: use internal "revstates" array to test if rev is a root

The main goal of this patch series is to reduce the use of PyXxx() function
that is likely to require ugly error handling and inc/decref. Plus, this is
faster than using PySet_Contains().

  revset #0: 0::tip
  0) 0.004168
  1) 0.003678  88%

This patch ignores out-of-range roots as they are in the pure implementation.
Because reachable sets are calculated from heads, and out-of-range heads raise
IndexError, we can just take out-of-range roots as unreachable. Otherwise,
the test of "hg log -Gr '. + wdir()'" would fail.

"heads" argument is changed to a list. Should we have to rename the C function
as its signature is changed?

  $ 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
  unknown