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
#
# test for issue351
# Environement setup for MQ
echo "[extensions]" >> $HGRCPATH
echo "mq=" >> $HGRCPATH
#Repo init
hg init
hg qinit
echo b > b
hg ci -A -m foo
echo cc > b
hg qnew -f foo.diff
echo b > b
hg qrefresh
hg debugindex .hg/store/data/b.i