directory nested angle bracket component breaks the template compiler

Code:

```
{{#docs-demo as |demo|}}
{{#demo.example name='important'}}
Foo
{{/demo.example}}

{{demo.snippet 'important'}}
{{/docs-demo}}
```

Error:
```
Template Compiler Error (broccoli-persistent-filter:TemplateCompiler) in dummy/templates/docs/components/buttons.hbs

Closing tag `Button::Important` (on line 6) without an open tag.
```
---------

This bug does not occur if the component is self closing:
```
{{#docs-demo as |demo|}}
{{#demo.example name='important'}}

{{/demo.example}}

{{demo.snippet 'important'}}
{{/docs-demo}}
```