[3.9] bpo-41056: Fix a possible MemoryError leak within zoneinfo. (GH-21007)

This was detected by our Coverity scan as a REVERSE_INULL issue.

Automerge-Triggered-By: @gpshead
(cherry picked from commit d780fa7)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
2 files changed