convert: make contents of "extra" dict available from sources, for sinks. This breaks hash preservation for hg->hg conversion, as each converted change gets a convert_revision item added to its extra dict. Ugh.

#!/bin/sh

hg init
mkfifo p

hg serve --stdio < p &
P=$!
(echo lock; echo addchangegroup; sleep 5) > p &
Q=$!
sleep 3
kill -HUP $P
wait
echo .hg/* .hg/store/*