This prevents duplicate sessions from being added to Day during a rebuild, but is still not
the root cause. The next step will be to address the attempted duplication in Machine.
This introduces a very slight change UI behavior, where the user
will receive an alert if their machine has a supported family/version
but is a model number for which we don't have any test data.
Also, the user alert for an unsupported machine has been updated
to align with the actual underlying parsing limitations. It's
possible this will create some new warnings, but it doesn't seem
like any such machines would have worked anyway, in which case
an explanatory message is an improvement.
The "untested" alert will happen on import once per launch of OSCAR.
Ideally this would only happen the first time an untested machine is
imported, but that will require figuring out how to serialize an
additional value in the user's machine profile.
