[PATCH 1 of 2] filemerge: add support for multiple merge tool versions (RFC)

[Matt Mackall]

On Wed, 2015-12-16 at 01:07 -0600, Mathias De Maré wrote:
> # HG changeset patch
> # User Mathias De Maré <mathias.demare at gmail.com>
> # Date 1450249051 -3600
> #      Wed Dec 16 07:57:31 2015 +0100
> # Node ID 958659a81ec2cea8037e4e8ba1bf9841c0272f88
> # Parent  7e8a883da1711008262150bb6f64131812de3e0b
> filemerge: add support for multiple merge tool versions (RFC)

ENODOCS. But from trying to parse the test, it seems a little complex.
It'd be much simpler to have something like:

mytoolwithauto = /usr/bin/mytool
mytoolwithauto.featurecheck = "--help", ".*--auto-merge.*"

Even so, invoking a gui tool to get its version or help can be pretty
expensive (possibly seconds) compared to just searching the path and we
have no infrastructure to remember what we've already learned from file
to file in a merge. 

-- 
Mathematics is the supreme nostalgia of our time.