rainbow gem failure on Ruby 2.4

[ain]

On Ruby 2.4 I'm getting a following native extension build failure:

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    can't modify frozen String

Gem files will remain installed in /usr/local/rvm/gems/ruby-2.4.0/gems/rainbow-2.2.1 for inspection.
Results logged to /usr/local/rvm/gems/ruby-2.4.0/extensions/x86_64-linux/2.4.0/rainbow-2.2.1/gem_make.out

An error occurred while installing rainbow (2.2.1), and Bundler cannot continue.
Make sure that `gem install rainbow -v '2.2.1'` succeeds before bundling.

Platform: phusion/passenger-ruby24

[ain]

Seems to be an issue discussed at ku1ik/rainbow#49

[ain]

I also noticed 2.4 test is commented out, was this one of the reasons?

[CloCkWeRX]

Pin to <= 2.2.1 for now is the fastest workaround; thought I'd done it for ffcrm but apparently not!

[CloCkWeRX]

I also noticed 2.4 test is commented out, was this one of the reasons?

7af4f5a - I suspect so.

[CloCkWeRX]

@ain take a look at the above linked ticket; think you are going to have a bad time with Ruby 2.4.0 and Rails 4.2.X for a bit.

Rails 5 for ffcrm is probably not guaranteed to work happily either without work.

[ain]

Thanks a lof for the prompt support!