Attempting to open a file before it is created turns out not to be a
good idea.  Moved all the file opening inside the wait_until lambdas
(after extracting them into a standalone helper function, since you
can't use the with statement inside a lambda).

Also fixed test failure on Python 3.3 (r.write() returns the number of
bytes written).

Added an XXX about a possible hang while opening ClientStorage, in case
something went wrong.  I'm not sure how to fix that.

The tests fail without that version.

Timeout error showing up in log before the 'client has newer' error.

Match ZODB commit 69c18075dafca12a7bb4d431751d40c2f0f2884e.

Explicitly install the 'random2' dependency.

ClientStorage.py can deadlock in tpc_begin

Used to be "TypeError: str object is not an iterator".