[PATCH 6 of 6 RFC] perf: define formatter locally if Mercurial is earlier than 2.2

[Matt Mackall]

On Fri, 2016-06-17 at 19:04 +0200, Pierre-Yves David wrote:
> The code itself seems mostly good to me (I need a second pass) but I'm a
> bit confused about why we want to make perf.py backward compatible? Old
> version of Mercurial can use the old version of the perf extension,
> isn't that enough? I'm curious about your use case here.

When you add new perf tests, you want to run them against historic hg. I hit
this regularly.

-- 
Mathematics is the supreme nostalgia of our time.