Message 301066 - Python tracker

This change suddenly made detection of reference leaks a lot less effective.  Now if you have a single 0 in the deltas list, it will consider there is no reference leak, even though all other values might be > 0.

See https://bugs.python.org/issue31317#msg301064 for an example.

Victor, it would be nice if you could find a less brutal heuristic.