eg https://aus4.mozilla.org/update/3/Firefox/29.0/20140421221237/Darwin_x86_64-gcc3-u-i386-x86_64/en-US/beta/Darwin%2013.1.0/default/default/update.xml?force=1 returns <patch type="complete" URL="http://download.mozilla.org/?product=firefox-33.0b1-complete&os=osx&lang=en-US" .... Should end '&force=1'. I can't see balrog.ini on prod to see if it's a config or code issue, but may be fallout from the blob refactoring. Blocks comparison of aus3.m.o and aus4.m.o.
Seems likely that this is my fault, I'll look into it soon. The worrying part is that tests didn't catch it :S.
Spoke to cturra on IRC before I read your reply, and it turns out we're not defining specialforcehosts for aus4.m.o at the moment. So the tests are probably in the clear.
Fixed by the config change in bug 1064622.