pandoc/test/command/512.md

```
% pandoc -f rst
`click here`__ or `click here`__

.. _link1: http://www.example.com/
.. _link2: http://johnmacfarlane.net/pandoc/

__ link1_
__ link2_
^D
<p><a href="http://www.example.com/">click here</a> or <a href="http://johnmacfarlane.net/pandoc/">click here</a></p>
```

Multiple indirection:

```
% pandoc -f rst
`click here`__

.. _link1: link2_
.. _link2: http://johnmacfarlane.net/pandoc/

__ link1_
^D
<p><a href="http://johnmacfarlane.net/pandoc/">click here</a></p>
```

Loop detection:

```
% pandoc -f rst
`click here`__

.. _link1: link2_
.. _link2: link1_

__ link1_
^D
[warning] Circular reference 'link1' at line 1 column 15
<p><a href="">click here</a></p>
```