NoMethodError: undefined method `last_comment’ after upgrading to rake 11

Rake 11.0.1 removes the last_comment method which Rails 2.3 rspec-core (< 3.4.4) uses. Therefore until/if a patch is released we need to pin rake to an older version in Gemfile:

gem 'rake', '< 11.0'

then:

$ bundle update
$ grep rake Gemfile.lock 
      rake
      rake (>= 0.8.7)
    rake (10.5.0)
      rake
  rake (< 11.0)

We are now using rake 10.5.0 which still has the last_comment method and our rake tasks will work again.

UPDATE: This has now been fixed in rspec, so the only thing necessary should be updating rspec.