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

echo "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH

hg init a
cd a

echo 'base' > base
hg ci -Ambase -d '1 0'

hg qnew -mmqbase mqbase

hg qsave
hg qrestore 2