Unknown file type error with .pyx file
<p>I'm trying to build a Python package (pyregion) that contains a *.pyx file and error comes during the build process. Checking out the below output:</p>

<pre><code>$ python setup.py build
running build
running build_py
creating build
creating build/lib.macosx-10.5-x86_64-2.7
....
running build_ext
building 'pyregion._region_filter' extension
C compiler: gcc -fno-strict-aliasing -fno-common -dynamic -arch x86_64 -DNDEBUG -g -O3 -arch x86_64

error: unknown file type '.pyx' (from 'src/_region_filter.pyx')
</code></pre>

<p>Any ideas on what the issue could be? Just to note, I'm using the Enthought build of Python (7.1) on OSX with the latest Xcode (4.1). </p>

<p>Cheers </p>
