add merge command. means same thing as "update -m".
repo.addchangegroup method now returns number of heads modified and added,
so command line can tell whether update or merge needed. this makes
tiny change to ssh wire protocol, but change is backwards compatible.
pull command now returns 0 if no changes to pull.
#!/bin/sh
#
# Corrupt an hg repo with a pull started during an aborted commit
#
# Create two repos, so that one of them can pull from the other one.
hg init source
cd source
touch foo
hg add foo
hg ci -m 'add foo'
hg clone . ../corrupted
echo >> foo
hg ci -m 'change foo'
# Add a hook to wait 5 seconds and then abort the commit
cd ../corrupted
echo '[hooks]' >> .hg/hgrc
echo 'pretxncommit = sleep 5; exit 1' >> .hg/hgrc
# start a commit...
touch bar
hg add bar
hg ci -m 'add bar' &
# ... and start a pull while the commit is still running
sleep 1
hg pull ../source 2>/dev/null
# see what happened
wait
hg verify