test-bundle2: add obsolescence information to be exchanged
To introduce a bundle2 way to exchange obsolescence markers, we need to
have some information available to exchange. Introduce markers relevant
to changesets involved in the exchange. The new markers reference the
changesets as successor nodes of clowny (nonexistent) hashes so that
other than being exchanged they have no effect.
We introduce them in two waves as push is expected to be smart about the
number of markers it exchanges sooner than pull.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state