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?
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.