Committed as: rev5732:0e6ed3d72f92 

Fixes to testing for the rest code are in rev5733:62bdcb874433 and
rev5734:5cd9ac3daed7.  These patches attempt to test the retry code that
wraps the opening of an existing database. All of the tests
for otk/session db create a new database during the test. The
session/otk db class is never reloaded. So the code path that runs
is always the one that creates and opens the database and never
the one that opens an existing database.

I haven't figured out how to cause the open call to fail to trigger the
exception handling routines. I could use a pointer from somebody with
better python fu than I have.