tests/test-issue612.t

changegroup: move revchunk() from narrow

The monkeypatched revchunk for ellipses serving is a
completely independent implementation. We model it as such
in the changegroup code. revchunk() is now a simple proxy
function.

Again, I wish we had better APIs here. Especially since this
narrow code is part of cg1packer and cg1packer can't be used
with narrow. Class inheritance is wonky. And I will definitely
be making changes to changegroup code for delta generation.

As part of the code move, `node.nullrev` was replaced by
`nullrev`. And a reference to `orig` was replaced to call
`self._revchunknormal` directly.

Differential Revision: https://phab.mercurial-scm.org/D4063

https://bz.mercurial-scm.org/612

  $ hg init
  $ mkdir src
  $ echo a > src/a.c
  $ hg ci -Ama
  adding src/a.c

  $ hg mv src source
  moving src/a.c to source/a.c

  $ hg ci -Ammove

  $ hg co -C 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo new > src/a.c
  $ echo compiled > src/a.o
  $ hg ci -mupdate
  created new head

  $ hg status
  ? src/a.o

  $ hg merge
  merging src/a.c and source/a.c to source/a.c
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg status
  M source/a.c
  R src/a.c
  ? src/a.o