My suggestion with transitions is: Having a short look, which packages are involved could help a lot. pipers way might work, but is to destructive for me
aptitude search '~i~Dqtbase-abi-5-9' -F "%p"
would give a list of packages which are depend on the old abi.
apt policy $(aptitude search '~i~Dqtbase-abi-5-9' -F "%p")
Would list all packages and where they come from. nuff said.