title: unpacking, editing and rebuilding ruby gem
body: <p>I need to edit the contents of a ruby gem, call him <strong><em>a.gem</em></strong>.<br/>
  I used <code>gem unpack a.gem</code> ,got the insides of it, and <code>gem unpack --spec a.gem</code> to get a <em>.gemspec</em>.<br/>
  I've added a new file, updated the <code>files:</code> section of the <em>.gemspec</em> to include it. <br/>I've put <em>a.gemspec</em> inside the folder resulted from unpacking the gem. <br/><br/>
  Now I'm try to <code>gem build a.gemspec</code>, and I'm getting the following error:<br/></p>
  
  <pre><code>Invalid gemspec in [logstash-output-jdbc-5.2.1-java.gemspec]: logstash-output-jdbc-5.2.1-java.gemspec:1: syntax error, unexpected tSYMBEG, expecting keyword_do or '{' or '('
  --- !ruby/object:Gem::Specification
                   ^
  logstash-output-jdbc-5.2.1-java.gemspec:2: syntax error, unexpected ':', expecting end-of-input
  name: logstash-output-jdbc
       ^
  ERROR:  Error loading gemspec. Aborting.
  </code></pre>
  
  <p>What am I doing something wrong? I'm not a ruby programmer and I just need to edit something there.</p>