title: Grunt jade error
body: <p>Whenever I run grunt jade I get an error:</p>
  
  <pre><code>Warning: pattern.indexOf is not a function Use --force to continue.
  </code></pre>
  
  <p>Now here is my jade task:</p>
  
  <pre><code>    jade: {
          options: {
              pretty: true
          },
          all: {
              files: {
                  expand:true,
                  cwd: 'src/static/jade',
                  ext: "html",
                  src: ['src/static/jade/**/*.jade', '!src/static/jade/_includes'],
                  dest: 'build/'
              }
          }
      }
  </code></pre>
  
  <p>So basically I am trying to take the jade files in <code>src/static/jade</code> (including subdirs, except <code>_include</code>) and put them in <code>build</code>, keeping the directory structure. I have tryed commenting the <code>expand</code> line, however it gives me:</p>
  
  <pre><code> Warning: Unable to read "src/static/jade" file (Error code: EISDIR). Use --force to continue.
  </code></pre>
  
  <p>Perhaps I am going about this the wrong way. How should I fix this?</p>