CVE-2026-17084: use the Unicode 3.2.0 codepoint attributes required by RFC 3454
for the stringprep B.2/B.3 mappings instead of the running interpreter's, so
IDNA 2003 encodes domain names consistently
CVE-2026-87910: skip the member in tarfile's link-extraction fallback when
either filter call returns None, instead of discarding the first call's result
CVE-2026-19672: normalize '..' components in tarfile member names so the tar
and data extraction filters no longer create intermediate directories outside
the destination
CVE-2026-12003: remove the VPATH-relative Modules/Setup.local build landmark
fallback from getpath, making pybuilddir.txt the sole source-tree indicator