rust-re2: add wrapper for calling Re2 from Rust
This assumes that Re2 is installed following Google's guide. I am not sure
how we want to integrate it in the project, but I think a follow-up patch would
be more appropriate for such work.
As it stands, *not* having Re2 installed results in a compilation error, which
is a problem as it breaks install compatibility. Hence, this is gated behind
a non-default `with-re2` compilation feature.
Differential Revision: https://phab.mercurial-scm.org/D7910
Issue351: mq: qrefresh can create extra revlog entry
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
$ echo b > b
$ hg ci -A -m foo
adding b
$ echo cc > b
$ hg qnew -f foo.diff
$ echo b > b
$ hg qrefresh
$ hg debugindex b
rev linkrev nodeid p1 p2
0 0 1e88685f5dde 000000000000 000000000000