2d9885c introduced some regressions. This addresses those.
* Don't throw return type notice or session write failure when in an exception
* Fix tests to properly return true/false since null is no longer falsy/successy
* Rerecord a few tests to accomodate difference in raised warnings
These hopefully test a reasonable set of basic, error and variations for
the twenty or so session functions. Note however that they do not
test all the session configuration settings.
