pipeline_test.cpp contains a assertPipelineOptimizesTo function which constructs and returns a Pipeline instance.

To construct it, assertPipelineOptimizesTo creates a local-scoped OperationContext which is associated to the ExpressionContext for that Pipeline. But since the OperationContext is local-scoped, it is destroyed when the function returns, which means that the Pipeline returned by the function contains a dangling pointer to the destroyed OperationContext.

Currently this is harmless, however as part of SPM-4048 we intend to use that OperationContext to check feature flags, so we need to ensure that the lifetime of the Pipeline is contained within that of the OperationContext.