Merging PR 6517 for issue33305 exposed a leak in the compiler:

https://buildbot.python.org/all/#/builders/1/builds/280

$ ./python -m test -R 3:3 test_compile test_grammar
Run tests sequentially
0:00:00 load avg: 1.95 [1/2] test_compile
beginning 6 repetitions
123456
......
test_compile leaked [15, 16, 15] memory blocks, sum=46
0:00:14 load avg: 1.97 [2/2/1] test_grammar -- test_compile failed
beginning 6 repetitions
123456
......
test_grammar leaked [50, 50, 50] memory blocks, sum=150
test_grammar failed

== Tests result: FAILURE ==

2 tests failed:
    test_compile test_grammar

Total duration: 15 sec 226 ms
Tests result: FAILURE


This branch was not common, but after issue33305 it has became more common and heavily tested.