allow TraceableEventDispatcher to reuse event instance in nested events
bug #9750 allow TraceableEventDispatcher to reuse event instance in nested events (evillemez)

This PR was merged into the 2.3 branch.

Discussion
----------

allow TraceableEventDispatcher to reuse event instance in nested events

| Q                       | A
| -------------            | ---
| Bug fix?             | yes
| New feature?      | no
| BC breaks?        | no
| Deprecations?    | no
| Tests pass?       | yes
| Fixed tickets      | #9710, #9727
| License              | MIT

Commits
-------

454ce16 allow TraceableEventDispatcher to reuse event instance in nested events