New format branch broke compatibility

[Gustavo Niemeyer]

Not sure if it was intentional, but given that Robert just asked
if it'd be ok to break compatibility for some other reason, I
decided it'd be worth mentioning.

The last bzr.newformat branch breaks compatibility with previous
repositories using the new format storage, due to that line
on branch.py:

  self.revision_store = get_store('revision-store', compressed=True)

Revisions used to be compressed, so this will yield the follownig
error when used in a previous repository:

bzr: ERROR: Branch _Branch('/home/niemeyer/src/bzr.mergelog/repos1')
has no revision gustavo at niemeyer.net-20050929163758-7163c414d477c5a2
  at /home/niemeyer/src/bzr.mergelog/bzrlib/branch.py line 718, in
get_revision_xml_file()
  see ~/.bzr.log for debug information

If that's intentional, I don't think it's even necessary to include
upgrade code. Just mention that 

  for file in .bzr/revision-store/*.gz; do gunzip $file; done

is necessary.

Cheers!

-- 
Gustavo Niemeyer
http://niemeyer.net