Actually, it turned out that sci-libs/freesteam was additionally
suffering from a different bug. After ruling that out, the patch
in -r3 works fine.
#--- END OF EXAMPLES ---
# Michał Górny <mgorny@gentoo.org> (16 May 2018)
-# The patch to force user's *FLAGS does not handle --param flags
-# correctly, and I don't seem to be able to get it right. Use -r1
-# instead. Help appreciated.
+# Broken *FLAGS handling. Use -r3 instead.
=dev-util/scons-3.0.1-r2
# Michał Górny <mgorny@gentoo.org> (15 May 2018)