tests/test-extra-filelog-entry.t

bundle2: support chunk iterator as part data

When the `part.data` attribute is an iterator, we assume it is an iterator of
chunks and use it.

We use a chunkbuffer to yield chunks of 4096 bytes.

The tests are updated to use this feature.

Issue351: mq: qrefresh can create extra revlog entry

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

  $ hg init
  $ hg qinit

  $ echo b > b
  $ hg ci -A -m foo
  adding b

  $ echo cc > b
  $ hg qnew -f foo.diff
  $ echo b > b
  $ hg qrefresh

  $ hg debugindex b
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 1e88685f5dde 000000000000 000000000000 (re)