[PATCH] help: don't crash in keyword search if an extension fails to provide docs

[Yuya Nishihara]

On Wed, 10 Feb 2016 02:54:59 -0800, Simon Farnsworth wrote:
> # HG changeset patch
> # User Simon Farnsworth <simonfar at fb.com>
> # Date 1455097738 28800
> #      Wed Feb 10 01:48:58 2016 -0800
> # Node ID ab0871393d3e0827645371b3d764c268c7ebde94
> # Parent  a036e1ae1fbe88ab99cb861ebfc2e4da7a3912ca
> help: don't crash in keyword search if an extension fails to provide docs

Queued per Sean's review, thanks.

Can you add a test of extensions with no docstring?