(In reply to comment #0)

While trying to get a list of indef blocked IPs through ipb_user = 0
betacommands list (
http://tools.wmflabs.org/betacommand-dev/reports/enwiki_indef_ips.txt )
returned a number of weird non-IP entries.

Krenair was kind enough to compile a list of the 57 accounts involved.

It also seems like this issue is perhaps known since November 2008:
https://en.wikipedia.org/w/index.php?title=Special:
Log&offset=20081116011504&limit=33&type=block&user=MZMcBride

I wonder if these accounts can be registered or what would happen if they
were
to make edits.

Another question is how many similar accounts do other wikis have?

Krenair's list: http://pastebin.com/ymRvvyxP

It's pretty unclear to me what is requested in the bug. Investigate if there is an issue in MediaWiki code? Fix some configuration on Wikimedia servers?

For the records, Krenair's query: [enwiki_p]> SELECT ipb_address FROM ipblocks WHERE ipb_user = 0 AND ipb_range_start = '' AND NOT ipb_address LIKE '%.%.%.%';

I'd request investigating the reason and fixing the problem.