[Bug runtime/17270] uprobes_onthefly.exp causing hang on ppc64

[Jonathan Lebon]

Hey David,

Glad you found the cause of the issue.

> 1) The "stap module notifier triggered in unexpected state 3" message happens
> when the session is shutting down but the uprobe hasn't been unregistered
> yet.

This can also occur if there is still a work item left on the workqueue after
we changed to the STAP_SESSION_STOPPING state. This is probably why this
error message occurs more frequently during stress subtests.

> I think we can change the code to not output this message if we in the
> STAP_SESSION_STOPPING state.

Agreed!

Jonathan