bundle: introduce per-engine compression level
If experimental.bundlecomplevel.$engine is set, prefer it over the
generic experimental.bundlecomplevel. Given that compression levels have
widely different meanings across engines, this allows much saner
configuration.
Differential Revision: https://phab.mercurial-scm.org/D3393
#require serve killdaemons
$ hg clone http://localhost:$HGPORT/ copy
abort: * (glob)
[255]
$ test -d copy
[1]
$ $PYTHON "$TESTDIR/dumbhttp.py" -p $HGPORT --pid dumb.pid
$ cat dumb.pid >> $DAEMON_PIDS
$ hg clone http://localhost:$HGPORT/foo copy2
abort: HTTP Error 404: * (glob)
[255]
$ killdaemons.py