FTBFS (+builds?build_state=failed) list unhelpful for folk fixing failures

[Daniel Hahler]

The list of failed builds [1] gets sorted so that the first entries (> 225 currently) state:
"Build started at an unknown time on an unknown build machine"

Since it's most interesting to see what failed recently, the newest entries (with known date), should get sorted to the top; and the unknown ones probably to the end.

1: https://launchpad.net/ubuntu/+builds?build_text=&build_state=failed&start=225&batch=75

Analysis
========

The build list serves many users, but the failed build list is really for folk fixing FTBFS issues, so tweaking the sort to help them makes sense. The unknowns seem to be security builds, which suggests either a permissions issue (why are we showing them?!) or if not that then it looks like NULLS FIRST in the sort order. Some query spelunking needed.

However a better way to address this might be a FTBFS report which only shows current failures (vs the build list which will show a failure even if the package has subsequently been biult).