hg: say 'hg update' instead of 'hg up' in merge status message
Includes the change to the message itself, along with several test
output files that also had to change.
#!/bin/sh
hg init repo
cd repo
touch foo
hg ci -Am 'add foo'
hg up -C null
# this should be stored as a delta against rev 0
echo foo bar baz > foo
hg ci -Am 'add foo again'
hg debugindex .hg/store/data/foo.i