Using the rust implementation of lazyancestors.

[Yuya Nishihara]

On Wed, 24 Oct 2018 18:43:11 +0300, Pulkit Goyal wrote:
> Recently Georges did some awesome work on reimplementing the lazyancestors
> interator in Rust which was/is in Python originally. The speedups mentioned
> in
> https://www.mercurial-scm.org/pipermail/mercurial-devel/2018-October/123779.html
> are insane.
> 
> I was not following the series closely when it was reviewed and also I
> don't have much knowledge about rust. Any help on how one can use these
> rust implementation will be greatly appreciated.

  $ make local HGWITHRUSTEXT=

and you're done. Eventually it will be a run-time option like
HGMODULEPOLICY=rust, but it's compile-time thing right now.