For example, we get failures if we try upgrading

• mypy.fswatcher.FileData python/mypy@f6332f5
• mypy.modulefinder.SearchPaths python/mypy@3bb691c

Also ref python/mypy#12708

Error manifests as a KeyError for the type of some field in the NamedTuple, but I also got segfaults when upgrading NamedTuples in mypyc itself