Create an extension to test bundle2 API

  $ cat > bundle2.py << EOF

  > """A small extension to test bundle2 implementation

  > 

  > Current bundle2 implementation is far too limited to be used in any core

  > code. We still need to be able to test it while it grow up.

  > """

  > 

  > import sys

  > from mercurial import cmdutil

  > from mercurial import bundle2

  > cmdtable = {}

  > command = cmdutil.command(cmdtable)

  > 

  >     """write a bundle2 container on standard ouput"""

  >         ui.write(chunk)

  > 

  > @command('unbundle2', [], '')

  > def cmdunbundle2(ui, repo):

  >     """read a bundle2 container from standard input"""

  >     unbundler = bundle2.unbundle20(sys.stdin)

  >     ui.write('options count: %i\n' % len(unbundler.params))

  >     parts = list(unbundler)

  >     ui.write('parts count:   %i\n' % len(parts))

  > EOF

  $ cat >> $HGRCPATH << EOF

  > [extensions]

  > bundle2=$TESTTMP/bundle2.py

  > EOF

The extension requires a repo (currently unused)

  $ hg init main

  $ cd main

  $ touch a

  $ hg add a

  $ hg commit -m 'a'

  $ hg bundle2

  HG20\x00\x00\x00\x00 (no-eol) (esc)

  $ hg bundle2 | hg unbundle2

  options count: 0

  parts count:   0

Test old style bundle are detected and refused

  $ hg bundle --all ../bundle.hg

  1 changesets found

  $ hg unbundle2 < ../bundle.hg

  abort: unknown bundle version 10

  [255]