Explicitly disallow caching + common_utility_include_dir.

Also added note to change log.

CHANGES.rst

@@ -25,6 +25,10 @@ Features added
 
 * The cython-mode.el script for Emacs was updated.  Patch by Ivan Andrus.
 
+* An option common_utility_include_dir was added to cythonize() to save
+  oft-used utility code once in a separate directory rather than as
+  part of each generated file.
+
 Bugs fixed
 ----------
 

Cython/Build/Dependencies.py

@@ -658,6 +658,8 @@ def cythonize(module_list, exclude=[], nthreads=0, aliases=None, quiet=False, fo
     if 'include_path' not in options:
         options['include_path'] = ['.']
     if 'common_utility_include_dir' in options:
+        if 'cache' in options:
+            raise NotImplementedError, "common_utility_include_dir does not yet work with caching"
         if not os.path.exists(options['common_utility_include_dir']):
             os.makedirs(options['common_utility_include_dir'])
     c_options = CompilationOptions(**options)