[ebuild U ] sys-libs/libunwind-1.2.1-r3::gentoo [1.2.1-r1::gentoo] USE="static-libs -debug -debug-frame -doc -libatomic -lzma" 763 KiB * Searching all installed packages for file collisions... * * Press Ctrl-C to Stop * * sys-libs/libunwind-1.2.1-r1:0::gentoo * /usr/lib64/libunwind-coredump.a * /usr/lib64/libunwind-coredump.la * /usr/lib64/libunwind-coredump.so.0.0.0 * /usr/lib64/libunwind-ptrace.a * /usr/lib64/libunwind-ptrace.la * /usr/lib64/libunwind-ptrace.so.0.0.0 * /usr/lib64/libunwind-setjmp.a * /usr/lib64/libunwind-setjmp.la * /usr/lib64/libunwind-setjmp.so.0.0.0 * /usr/lib64/libunwind-x86_64.a * /usr/lib64/libunwind-x86_64.la * /usr/lib64/libunwind-x86_64.so.8.0.1 * /usr/lib64/libunwind.a * /usr/lib64/libunwind.la * /usr/lib64/libunwind.so.8.0.1 * /usr/lib64/pkgconfig/libunwind-coredump.pc * /usr/lib64/pkgconfig/libunwind-generic.pc * /usr/lib64/pkgconfig/libunwind-ptrace.pc * /usr/lib64/pkgconfig/libunwind-setjmp.pc * /usr/lib64/pkgconfig/libunwind.pc
well to be more precise: [binary NS ] sys-libs/libunwind-1.2.1-r3-1:7::gentoo [1.2.1-r1:0::gentoo] USE="static-libs -debug -debug-frame -doc -libatomic -lzma" 0 KiB It looks like the package moved from slot 0 to slot 7, and ... err ... can't install it twice
You might want to check with dev-portage@ why slotmove did not work for you: https://gitweb.gentoo.org/repo/gentoo.git/commit/profiles/updates/1Q-2020?id=192c9e77e35e91b3d03525ca5bab6d2e499e2f2c
Can this problem be reproduced today?