In a thread on d-vote Joerg Jaspert reports that ftpmaster sometimes
block a particular PGP fingerprint in a hurry.

Currently, the dgit-repos server, and the proposed t2u server, do not
have this information.  They should have it and honour it.

Joerg writes:

This seems like an appropriately lightweight answer.

I suggest the following details:

 * Make the dgit-repos-server program, which interprets the keyrings
   and dm permissions list, take an additional input file, which is
   the list of blocked fingerprints.

 * Update ftpmaster's processes to add a script which rsyncs the
   blocked fingerprint list.  Currently, to a suitable location on
   push.dgit.debian.org.  And, after t2u is deployed, to the t2u
   server too.  Using an rsync restricted command, as proposed.

 * Arrange to regularly test that this push of a new file can be done,
   in case the rsync restricted command rots.

Joerg, does that sound good to you?  Should the file be anything more
than a list of fingerprints without whitespace in hex ?

Ian.