Slightly different reason, same symptom:

mirror.pacific.net.au: @ERROR: max connections (15) reached -- try again later
Fri Dec 11 20:53:44 2009 mirror.pacific.net.au: starting
Fri Dec 11 20:53:45 2009 mirror.pacific.net.au: total files before scan: 2516
__DIE__: (=> /usr/bin/scanner 310 main::rsync_readdir => /usr/bin/scanner 972 
main::rsync_get_filelist)
mirror.pacific.net.au: [#2, id=102 pid=9324 exit: 65280]

issue 28 seems to be another case where the fallback to the next protocol doesn't 
happen as expected.

Normally, the scanner falls back to another protocol if an URL doesn't work. For some reason, this 
doesn't seem to happen when the (broken) opensuse-linuxmigratio.at mirror is being scanned. There, 
rsync is unreachable and HTTP is reachable (although it doesn't serve any files anymore). 

The scanner should fall back to HTTP and clean up the file list from there, but it doesn't happen:

 % mb scan migratio
Thu Oct  8 10:24:47 2009 opensuse-linuxmigratio.at: starting
Thu Oct  8 10:24:49 2009 opensuse-linuxmigratio.at: total files before scan: 98701
__DIE__: (=> /usr/bin/scanner 312 main::rsync_readdir => /usr/bin/scanner 971 main::rsync_get_filelist)
opensuse-linuxmigratio.at: connect: Connection refused
Completed in 1 seconds

As a result, the file list is not cleaned up and the mirror continues to be used.