Instead of providing the drop-in and placing it in u-u's preinst I think it would be better to fix apt instead.
Apt already exits on SIGUSR1 thus even when u-u is not installed this seems to work correctly.
I've uploaded apt and u-u for testing to ppa:rbalint/scratch, please give them a try.
Please upgrade apport in advance because the failure seems to be unrelated, but I'm going to check it again.
Instead of providing the drop-in and placing it in u-u's preinst I think it would be better to fix apt instead.
Apt already exits on SIGUSR1 thus even when u-u is not installed this seems to work correctly.
I've uploaded apt and u-u for testing to ppa:rbalint/ scratch, please give them a try.
Please upgrade apport in advance because the failure seems to be unrelated, but I'm going to check it again.