fix typo reported in bug #58 by Jorge Leitão

git-svn-id: http://svn.code.sf.net/p/pyx/code/trunk/pyx@3345 a4f5e268-e194-4f32-bce1-d30804cbbcc5
really fix typo reported in bug #58 by Jorge Leitão

git-svn-id: http://svn.code.sf.net/p/pyx/code/trunk/pyx@3346 a4f5e268-e194-4f32-bce1-d30804cbbcc5