load extensions only after the ui object has been completely initialized This fixes a traceback printed when hg tries to print another traceback after an extension fails to be loaded. Add a test for that.

#!/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
ls .hg