I'm upgrading the Mongoc version used in the Mongo Rust driver: https://github.com/thijsc/mongo-rust-driver/pull/59.

It seems something changed. When running the cleanup logic in the correct order, as enforced by Rusts ownership system there is now a double free:

 collection-4a23c99cd16c3bd9(28304,0x700001eb0000) malloc: *** error for object 0x7fc6ca40d3e0: pointer being freed was not allocated
collection-4a23c99cd16c3bd9(28304,0x700001eb0000) malloc: *** set a breakpoint in malloc_error_break to debug

This code worked correctly in earlier C driver versions. I don't see any notice about a change in the docs. Is this a bug?