Can't upload public key without comment

When I tried to upload a public key that has the comment removed, I get an error; something about block not found.

Start by reproducing the upload of a public key with its comment removed, recording the full error rather than only the reported “block not found” message. Trace the upload path from that failure and verify that the key is accepted without a comment, with a regression test if the relevant test location is identified.

Written by the indexing model from the issue text.