[Cython] Likely bug: compilation failure on aliased cimport + subclass interaction

[Matěj Laitl]

Hi,
it seems that when I do:
> cimport foo as f
> 
> cdef class DerivedClass(f.BaseClass):
>     pass

I get following compilation errors:
> 3:5: 'BaseClass' is not declared
> 3:5: 'f.pxd' not found
which looks like a bug to me.

When I use plain "cimport foo" + "foo.BaseClass" or "from foo cimport 
BaseClass" + "BaseClass", it works as expected. Cython version 
0.20dev add8091340e (git describe: 0.19-324-gadd8091)

I'm attaching a more complete testcase which I'll also submit as a review 
request for convenience.

Regards,
	Matěj Laitl