I guess it had to do something with libpam-kwallet-common vs. pam-kwallet-init.
Installed was pam-kwallet-init. This caused no problems with aptitude update+safe-upgrade (not even a "Package X is RECOMMENDED" warning, but I found that Discover (which I normally don't use) complained about wanting to install libpam-kwallet4 and libpam-kwallet5, and it needed libpam-kwallet-common for this, which again conflicts with the then-installed pam-kwallet-init.
So I just did "aptitude install libpam-kwallet-common", which then aptitude recognized as a conflict situation, proposing to resolve it by removing pam-kwallet-init and installing libpam-kwallet4 and 5.
Afterwards, all other packages (including kwin-x11 which I consider the culprit) upgraded flawlessly via Discover.
I guess it had to do something with libpam- kwallet- common vs. pam-kwallet-init.
Installed was pam-kwallet-init. This caused no problems with aptitude update+safe-upgrade (not even a "Package X is RECOMMENDED" warning, but I found that Discover (which I normally don't use) complained about wanting to install libpam-kwallet4 and libpam-kwallet5, and it needed libpam- kwallet- common for this, which again conflicts with the then-installed pam-kwallet-init.
So I just did "aptitude install libpam- kwallet- common" , which then aptitude recognized as a conflict situation, proposing to resolve it by removing pam-kwallet-init and installing libpam-kwallet4 and 5.
Afterwards, all other packages (including kwin-x11 which I consider the culprit) upgraded flawlessly via Discover.