Currently, regrtest considers that a test file leaks if at least one run increased or decreased the global reference counter. The problem is that in practice, Python is full of singletons, caches, and other jokes of the garbage collector, etc.

To reduce false alarms and focus more on real bugs, I suggest to change the reference difference checker from:

     def check_rc_deltas(deltas):
        return any(deltas)

to:

     def check_rc_deltas(deltas):
        return all(delta>=1 for delta in deltas)

It would allow to ignore false positives like:

* [3, 0, 0]
* [0, 1, 0]
* [8, -8, 1]