These are the packages that would be merged, in order:

Calculating dependencies ...

!!! Problem resolving dependencies for =app-emulation/xen-tools-4.20.2
 done!
Dependency resolution took 0.84 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=app-emulation/xen-tools-4.20.2" has unmet requirements.
- app-emulation/xen-tools-4.20.2::gentoo USE="hvm ipxe python qemu qemu-traditional rombios -api -debug -doc -lzma -ocaml (-ovmf) -pygrub -screen -sdl (-selinux) -static-libs -system-ipxe -system-qemu -system-seabios (-systemd) -zstd" PYTHON_SINGLE_TARGET="-python3_12 -python3_13"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( python_single_target_python3_12 python_single_target_python3_13 )

  The above constraints are a subset of the following complete expression:
    exactly-one-of ( python_single_target_python3_12 python_single_target_python3_13 ) ipxe? ( rombios ) ovmf? ( hvm ) pygrub? ( python ) rombios? ( hvm ) system-ipxe? ( rombios ) at-most-one-of ( ipxe system-ipxe ) at-most-one-of ( qemu system-qemu )