I don't know if this is intentional or not, but scl_package() redefines a bunch of RPM macros to change the prefix to the scl prefix, but not _usr (and thus not _usrsrc).

This impacts the build of gcc toolsets, picking up the annobin source from the system annobin rather than the newer version provided by gcc-toolset-XX

(Among others that means gcc-toolset-14-gcc fails to build as annobin uses gcc_option's that aren't there anymore)