[PATCH 1 of 5 V2] hook: add a 'hashook' function to test for hook existence

[Augie Fackler]

On Wed, Oct 11, 2017 at 04:02:27PM +0200, Boris Feld wrote:
> # HG changeset patch
> # User Boris Feld <boris.feld at octobus.net>
> # Date 1507460911 -7200
> #      Sun Oct 08 13:08:31 2017 +0200
> # Node ID 1a64b2bcd0209ea3b906f458818db6f29cebbcd7
> # Parent  4a6a337f9c682bdf1659295f871dc43ff33677ca
> # EXP-Topic b2.phases.hooks
> # Available At https://bitbucket.org/octobus/mercurial-devel/
> #              hg pull https://bitbucket.org/octobus/mercurial-devel/ -r 1a64b2bcd020
> hook: add a 'hashook' function to test for hook existence

queued, thanks

The rest of these have bitrotted. Could you rebase and resend them
(after seeing my comment on the next patch.) Thanks!