title: Why do I get error "undefined method `write_inheritable_attribute'" in my migration?
body: <p>I attempted to generate a migration like:</p>
  
  <pre><code>rails generate migration RemovefromGenotypes box:integer well:string
  </code></pre>
  
  <p>but then I get this error: </p>
  
  <pre><code>/usr/share/rails-ruby1.8/railties/lib/rails_generator/options.rb:32:in `default_options': undefined method `write_inheritable_attribute' for Rails::Generator::Base:Class (NoMethodError)
      from /usr/share/rails-ruby1.8/railties/lib/rails_generator/base.rb:90:in `&lt;class:Base&gt;'
      from /usr/share/rails-ruby1.8/railties/lib/rails_generator/base.rb:85:in `&lt;module:Generator&gt;'
      from /usr/share/rails-ruby1.8/railties/lib/rails_generator/base.rb:48:in `&lt;module:Rails&gt;'
      from /usr/share/rails-ruby1.8/railties/lib/rails_generator/base.rb:6:in `&lt;top (required)&gt;'
      from /home/caseyr/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
      from /home/caseyr/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
      from /usr/share/rails-ruby1.8/railties/lib/rails_generator.rb:34:in `&lt;top (required)&gt;'
      from /home/caseyr/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
      from /home/caseyr/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
      from /usr/share/rails-ruby1.8/railties/bin/rails:14:in `&lt;main&gt;'
  </code></pre>
  
  <p>I have no clue where to start to debug this, but would certainly appreciate it if anyone could point me in the right direction...</p>
  
  <p>Thanks!
  --rick</p>