Element query not recursing

Queries like `//node[@extension='true']` do not seem to recurse. For example, with the XML

```xml
<schema>
 <node>
  <name>First</name>
  <node extension="true">
   <name>Inner</name>
  </node>
 </node>
 <node extension="true">
  <name>Second</name>
 </node>
</schema>
```

the above query only returns the `Second` node, when it should also return the `Inner` node.