VariantTests drive the cache batch API and the real single-file store. The C1
vector was written by the code under test through that path; C# reads it and
rewrites it byte for byte, and the other runtimes' tests read the same bytes next.
The C0 tests that expected C# to refuse a v2 store now expect what C1 does with
it.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>