just for my curiosity... how did you fix the broken-package issue? What was the problem?
Geek stuff ahead

There were two problems:
1) There was a phony double 268 update - this shouldn't happen, but it happened. People who missed that update were affected by the other error.
2) There's code which handles differential updates. Because there were 2 releases of 268, but only one differential way to go from 268->278, it should work like this:
Do you have setup 268?
Download differential 268->278?
Perform diff
and now, if it fails (and it fails for all the people who missed the phony update), it should delete setup version 268 and download full 278. Instead it retained it and was thus unable to do the next step.
This bug only affects _next_ version. But, as we released _next_ _next_

version, bug is skipped and allows all to upgrade successfully.
BTW: Update to .280 worked like a charme 
Glad to hear that.