- src_prepare seds replaced bare "python3" with ${EPYTHON}, mangling
variable names like python3_version into python3.13_version.
- Use word-boundary regex (\<python3\>) so only command-name tokens
are substituted, leaving identifiers alone.
Closes: https://bugs.gentoo.org/975566
Signed-off-by: Huang Rui <vowstar@gmail.com>
