OK, so I've decided ugly #freeze is better than broken compatibility
with all string literals being frozen in Ruby 3... (and 3 is a long time
away)

Anyways, here's the tweaked version I'd like to commit based on your
patch:

	http://80x24.org/spew/20150916-Feature-11375-tweak%40v1/raw

interdiff of changes from your original patch at
https://bugs.ruby-lang.org/attachments/download/5400/ruby-changes.patch

	http://80x24.org/spew/20150916-Feature-11375-interdiff%40v1/raw