bundle2: feed a unbundle20 to the `processbundle` function
The unbundle can comes from multiple sources. (on disk file, peer, etc) and
(ultimately) of multiple type (bundle10, bundle20). The `processbundle` is no
longer in charge of creating the bundle.
http://mercurial.selenic.com/bts/issue1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..