[PATCH V2] merge: print status message before launching external merge tool

[Yuya Nishihara]

On Thu, 09 Feb 2017 16:24:27 -0800, Martin von Zweigbergk via Mercurial-devel wrote:
> # HG changeset patch
> # User Martin von Zweigbergk <martinvonz at google.com>
> # Date 1486661545 28800
> #      Thu Feb 09 09:32:25 2017 -0800
> # Node ID a5615bea1858aca891fcd3d7da6a477fc183f478
> # Parent  1f51b4658f21bbb797e922d155c1046eddccf91d
> merge: print status message before launching external merge tool

LGTM. Queued per Sean's review, thanks.