Each cookie binds to a domain name, multiple cookies can be set for the
same name if they are for different domain name. In this case, two
`session_id` cookies were set: (1) the first set right on the opener at
`opener.cookies[...] = ...`, (2) the second set upon inside of
`http.Request._save_session` because the session was rotated upon login.
The problem is that the former cookie (the one set on the opener, the
one *not* rotated) was used instead of the second cookie (the one
holding the registered user) in the subsequent queries. There is a long
comment explaining the same problem inside of
`odoo.tests.common.HttpCase.authenticate`, we used the same solution as
they did inside of `authenticate`: we diched the previous opener.
closesodoo/odoo#94773
Signed-off-by: Christophe Monniez (moc) <moc@odoo.com>