Not parsing <sec> tags within <content:encoded> tags

What steps will reproduce the problem?
1. Run feedparser on XML feed 
2. Entry contains:
     <content:encoded>
          <sec>
               <title>Something</title>
               <p>Article text here</p>
          </sec>
          <sec>
               <title>Related Title</title>
               <p>Copy of the second entry</p>
               <p>Additional text</p>
          </sec>
     </content:encoded>

3. Feedparser returns 'content' as ' ' 

What is the expected output? What do you see instead?
Would expect to see full content returned in 'content' - instead feedparser 
skips the <sec> tags and returns results as an empty string. 

What version of the product are you using? On what operating system?
Python 2.7.2 on Mac OS X 10.7.3 with feedparser 5.1.1

Please provide any additional information below.

Original issue reported on code.google.com by jason....@willowtreeapps.com on 27 Apr 2012 at 2:40

Reproduce the issue with the XML structure shown, using the feedparser entry content path as the starting point. Trace how content:encoded handles nested sec elements and verify that the returned content includes the section text rather than an empty string.