Make packages_in_version a dict in RPM import
Make packages_in_version a dict in RPM import

Create a dict for packages_in_version based on the pulp_href, which
should be unique among the packages in a repository version.

Also use that dict as a cache for the packages's being added.

ros-infrastructure/ros_buildfarm,ros-infrastructure/ros_buildfarm,ros-infrastructure/ros_buildfarm