grep: extend functionality, add man page entry, add unit test. walkchangerevs now returns a two-tuple. Its behaviour is also extensively commented. The annotate command's getname function has been factored out to a new function, trimname, so it can be shared between annotate and grep. The behaviour of grep has been beefed up, so that it now performs a number of useful functions.

#!/bin/sh

hg init
mkfifo p

hg serve --stdio < p &
P=$!
(echo lock; echo addchangegroup; sleep 5) > p &
Q=$!
sleep 1
kill -HUP $P
sleep 1
ls .hg