Remove superfluous open parenthesis.  Noticed by cocoatomo on docs@.
diff --git a/Doc/distutils/sourcedist.rst b/Doc/distutils/sourcedist.rst
index 9f7a38e..427b7b1 100644
--- a/Doc/distutils/sourcedist.rst
+++ b/Doc/distutils/sourcedist.rst
@@ -76,7 +76,7 @@
   :option:`packages` options
 
 * all C source files mentioned in the :option:`ext_modules` or
-  :option:`libraries` options (
+  :option:`libraries` options
 
   .. XXX getting C library sources currently broken---no
          :meth:`get_source_files` method in :file:`build_clib.py`!