The browser itself would get mostly cleaned up between tours, but the
session object would not get cleaned, and apparently in some cases
that could lead to an incoherent session: a tour would add data to the
session which the next tour (logging in as a different user) would
not (fully) override, leading to a session inconsistency and a Session
Expired exception during the tour.
Fix by not storing the session on the test object, the session is
created during authentication then set on the opener & browser.
Xavier Morel
dccbf425a1