dev-lang/python-exec: Do not copy meaningless Python 2 selection

Do not copy Python 2 version preference if Python 3 is the main
interpreter. It is not meaningful since we no longer support more than
one Python 2 version, and it will cause Python 2 to be preferred over
non-preferred versions of Python 3.

dev-lang/python-exec/python-exec-2.9999.ebuild

@@ -95,8 +95,8 @@ pkg_preinst() {
 			old_pythons+=( "$(<${config_base}/config)" )
 		fi
 
-		# then try specific py2/py3 selections
-		for py in 3 2; do
+		# then try specific py3 selection
+		for py in 3; do
 			local target=
 
 			if [[ -f ${config_base}/python${py} ]]; then