tests/bzr-definitions

revlog: move file writing to a separate function

Moves the code that actually writes to a file to a separate function in
revlog.py. This allows extensions to intercept and use the data being written to
disk. For example, an extension might want to replicate these writes elsewhere.

When cloning the Mercurial repo on /dev/shm with --pull, I see about a 0.3% perf change.
It goes from 28.2 to 28.3 seconds.

# this file holds the definitions that are used in various bzr tests

"$TESTDIR/hghave" bzr || exit 80

TERM=dumb; export TERM
echo '[extensions]' >> $HGRCPATH
echo 'convert = ' >> $HGRCPATH

glog()
{
    hg log -G --template '{rev}@{branch} "{desc|firstline}" files: {files}\n' "$@"
}

manifest()
{
    echo "% manifest of $2"
    hg -R $1 manifest -v -r $2
}