Apparently the with statement leaves a local variable pointing to the
BlobFile object, which holds a reference to the blog and prevents it
from being garbage collected.

largely due to:

* Different pickle size in Python
  (even for protocol 1, where new padding is added as far as I can tell.)

* Weak references do not seem to work correctly.

* When all tests are run, committing transactions fails. Probably some
  tests are not cleaning up enough after themselves.

The biggest issue remaining at this point is the fork of Python 3.3's
pickle to properly load Python 2 binary strings and adding back
``noload()`` to the unpickler.

failures left.

Thanks to Martin v. Loewis for having done some of the initial lifting
for a DZUG talk. I used a lot of his changes from this diff:

http://www.dcl.hpi.uni-potsdam.de/home/loewis/zodb/ZODB.diff

Applied all changes manually to make sure I do understand them and that
they are correct.

As always 90% of the work is to catch all places where we want to deal
with bytes instead of strings.

- Denominate files to indicate ReST.

- Drop .bzrignore.

- Add MANIFEST.in FBO users w/o setuptools_git.

Ensure that we use bytes literals for tid values.

Remove non-comment / docstring use of backticks.

repr() must return text, and we need bytes.

repr() must return text, and we need bytes.

       way that made other tests fail spuriously.

Fixed: An unneeded left-over setting in setup.py caused installation with
  pip to fail.

too fast.

too fast.

when running setup test.

Clean up dependency and setup test support.

(setup test fails because of circular imports)