Implements issue f9ec8a2ee4d52dd7102b001f92f9bea2a96322f9

Must apologize, I could of sworn the issue had no-one assigned against it when I opened this.

change to a single loop over rids ops

This should make the output a little more obvious for each rid being seeded.

Changes:

• Use NonEmpty for RIDs
• Ensure that a failed fetch does not exit
• Add a CLI test to ensure it works
• Use for directly rather than iter().copied()

Changes:

• Change help doc to [<rid>...]
• Remove eprintlns

Changes:

• Accidentally pushed master :facepalm:

Rebase