tests/test-rollback

mq: some improvements to header rewriting (closes #690)

Tested with qrefresh -m against the mm series.

#!/bin/sh

mkdir t
cd t
hg init
echo a > a
hg add a
hg commit -m "test" -d "1000000 0"
hg verify
hg parents
hg status
hg rollback
hg verify
hg parents
hg status