'nss' in the following code is moved in a QueryRequest object and then referenced again when creating an ExtensionsCallbackReal instance. 

https://github.com/mongodb/mongo/blob/4b880132b11c16a4a0cba4e5c3ce77892dd01f7c/src/mongo/db/commands/plan_cache_commands.cpp#L88-L94

This has the potential to cause problems, as ExtensionsCallbackReal uses this namespace in construction of a TextMatchExpression, which then obtains db and collection locks on the namespace.