fix setting of directive 'set_initial_path' in pyximport after renaming it in the compiler

pyximport/pyxbuild.py

@@ -60,9 +60,9 @@ def pyx_to_dll(filename, ext = None, force_rebuild = 0,
         if ext.name == '__init__' or ext.name.endswith('.__init__'):
             # package => provide __path__ early
             if not hasattr(ext, 'cython_directives'):
-                ext.cython_directives = {'set_initial_path_from_source' : True}
-            elif 'set_initial_path_from_source' not in ext.cython_directives:
-                ext.cython_directives['set_initial_path_from_source'] = True
+                ext.cython_directives = {'set_initial_path' : 'SOURCEFILE'}
+            elif 'set_initial_path' not in ext.cython_directives:
+                ext.cython_directives['set_initial_path'] = 'SOURCEFILE'
 
     if HAS_CYTHON and build_in_temp:
         args.append("--pyrex-c-in-temp")