title: Error while installing the mimemagic in rails
body: <p>I am using rails 4.2.4 and try to install paperclip gem in my application. After editing my gem file when I run bundle install.Then I got the error.</p>
  
  <pre><code>Bundler::GemspecError: Could not read gem at /home/darkpasenger/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/cache/mimemagic-0.3.0.gem. It may be corrupted.
  </code></pre>
  
  <p>An error occurred while installing mimemagic (0.3.0), and Bundler cannot continue.</p>
  
  <p>Make sure that <code>gem install mimemagic -v '0.3.0'</code> succeeds before bundling.</p>
  
  <p>So I run the command <code>gem install mimemagic -v '0.3.0</code>.Then again I got the error.</p>
  
  <pre><code>ERROR:  Error installing mimemagic:
  invalid gem: package is corrupt, exception while verifying: undefined method `size' for nil:NilClass (NoMethodError) in /home/darkpasenger/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/cache/mimemagic-0.3.0.gem
  </code></pre>
  
  <p>Please help me out to fix this problem. </p>