Things like LLVM (bug 916098) and Qt (bug 836726, https://forums.gentoo.org/viewtopic-t-1165995.html, etc) need to be updated as a whole as much as possible. While this is often another bug (e.g. some missing dependency, or Portage not getting the merge order right), it's still painful when saying KDE Plasma as if you're mid-Qt upgrade, you won't be able to open new applications. Sometimes, you might get something like: 1) dev-qt/qtcore 2) sys-devel/gcc 3) dev-qt/qtgui so the window of breakage is unnecessarily large. As a hint to the scheduler, we might be able to model stable groups [0][1] as weak dependencies which we immediately kill off in e.g. ignore_priority, but as a hint to collect them together where possible. [0] https://marc.info/?l=gentoo-dev&m=168951940606443&w=2 [1] metadata/stabilization-groups in ::gentoo, we already have a bunch
