Fix reference leak hunting in regrtest: compute also deltas (of
reference count, allocated memory blocks, file descriptor count)
during warmup, to ensure that everything is initialized before
starting to hunt reference leaks.
Other changes:
* Replace gc.collect() with support.gc_collect()
* Move calls to read memory statistics from dash_R_cleanup() to
dash_R()
* Pass regrtest 'ns' to dash_R()
* dash_R() is now more quiet with --quiet option (don't display
progress).
* Precompute the full range for "for it in range(repcount):" to
ensure that the iteration doesn't allocate anything new.
* dash_R() now is responsible to call warm_caches().
When regrtest in run inside IDLE, sys.stdout and sys.stderr are not
TextIOWrapper objects and have no file descriptor associated:
sys.stderr.fileno() raises io.UnsupportedOperation.
Disable faulthandler and don't replace sys.stdout in that case.
Issue #26538: libregrtest: Fix setup_tests() to keep module.__path__ type
(_NamespacePath), don't convert to a list.
Add _NamespacePath.__setitem__() method to importlib._bootstrap_external.
Victor Stinner
Ned Deily
Victor Stinner
Steve Dower