Module integrity is not preserved at copy time
In Pulp 2.19 copying modules does not automatically copy over rpms.
Using recursive:True tries to dep solve and copies not only rpms but dependent module streams and their dependent rpms (could be a a fairly expensive operation.)
To preserve module integrity and help users not to break module content easily, all available artifacts should always be copied (without their dependencies). No error is raised if any artifacts are unavailable in a source/destination repo.
To include dependencies, one still should use --recursive or --recursive-conservative flag.