Ruby 1.9 -Ku, mem_cache_store and invalid multibyte escape error

Originally this bug was posted here: https://rails.lighthouseapp.com/projects/8994/tickets/5713-ruby-19-ku-incompatible-with-mem_cache_store And now, as we've run into the same issue, I'll copy here a question from that issue, hoping someone have an answer already: When Ruby 1.9 is started in unicode mode (-Ku), mem_cache_store.rb fails to parse:

/usr/local/ruby19/bin/ruby -Ku /usr/local/ruby-1.9.2-p0/lib/ruby/gems/1.9.1/gems/
  activesupport-3.0.0/lib/active_support/cache/mem_cache_store.rb
/usr/local/ruby-1.9.2-p0/lib/ruby/gems/1.9.1/gems/activesupport-3.0.0/lib/active_support/
  cache/mem_cache_store.rb:32: invalid multibyte escape: /[\x00-\x20%\x7F-\xFF]/

Our case is practically identical: when you set config.action_controller.cache_store to :mem_cache_store, and try to run tests, console, or server, you recieve this in return:

/Users/%username%/.rvm/gems/ruby-1.9.2-p0/gems/activesupport-3.0.1/lib/active_support/
  cache/mem_cache_store.rb:32: invalid multibyte escape: /[\x00-\x20%\x7F-\xFF]/

An开发者_StackOverflowy ideas how this can be avoided?..

---

Ruby 1.9 in unicode mode will attempt to interpret the regular expression as unicode. To avoid this you need to pass the regular expression option "n" for "no encoding":

ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n

Now we have our raw 8-bit encoding (the only thing Ruby 1.8 speaks) as intended:

ruby-1.9.2-p136 :001 > ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n.encoding
=> # <Encoding:ASCII-8BIT>

Hopefully the Rails teams fixes this, for now you have to edit the file.