Taking into account the last time the builder built successully it must have happened in some of these commits:

b38b2fa021 Document importlib.metadata.PackagePath.locate method (GH-25669)
4a85718212 bpo-43970: Optimize Path.cwd() in pathlib by not instantiating a class unnecessarily (GH-25699)
15d3861856 bpo-37903: IDLE: Shell sidebar with prompts (GH-22682)
103d5e420d bpo-28254: _posixsubprocess uses PyGC_Enable/PyGC_Disable (GH-25693)
3b52c8d66b bpo-43908: Add Py_TPFLAGS_IMMUTABLETYPE flag (GH-25520)
3cc481b9de bpo-28254: Add a C-API for controlling the GC state (GH-25687)
baecfbd849 bpo-43757: Make pathlib use os.path.realpath() to resolve symlinks in a path (GH-25264)
859577c249 bpo-41559: Change PEP 612 implementation to pure Python (#25449)
c1a9535989 bpo-43955: Handle the case where the distutils warning has already been triggered (GH-25675)
4c49be7668 bpo-43959: clarify the documentation of the PyContextVar C-API (GH-25671)
fe52eb6219 bpo-43961: Fix test_logging.test_namer_rotator_inheritance() (GH-25684)
32c5a17444 bpo-43962: Fix _PyInterpreterState_IDIncref() (GH-25683)
21b02b5f40 bpo-43960: test_pdb resets breakpoints (GH-25673)
db0c5b786d bpo-43776: Remove list call from args in Popen repr (GH-25338)
f9bedb630e bpo-41486: Faster bz2/lzma/zlib via new output buffering (GH-21740)
a5e64444e6 bpo-43963: Add _signal module state (GH-25676)
5c84bb506a bpo-37751: Update `codecs.register()` doc. (GH-25643)