Merged solution for #11786 from 2.6

diff --cc Doc/library/configparser.rst
index e8eb3841c5603d5c83026abd245b2eb64b4fc939,7f68de762ff95289a8e850de66689da97609b0b1..3536f3efb6b34c1381147b4a5c6c9840c9612b22
--- 1/Doc/library/configparser.rst
--- 2/Doc/library/configparser.rst
+++ b/Doc/library/configparser.rst
@@@ -89,13 -79,12 +89,16 @@@ write-back, as will be the keys within 
     The basic configuration object.  When *defaults* is given, it is initialized
     into the dictionary of intrinsic defaults.  When *dict_type* is given, it will
     be used to create the dictionary objects for the list of sections, for the
 -   options within a section, and for the default values.  This class does not
 +   options within a section, and for the default values.  When *allow_no_value*
 +   is true (default: ``False``), options without values are accepted; the value
 +   presented for these is ``None``.
 +
 +   This class does not
     support the magical interpolation behavior.
  
+    All option names are passed through the :meth:`optionxform` method.  Its
+    default implementation converts option names to lower case.
+ 
     .. versionadded:: 2.3
  
     .. versionchanged:: 2.6
@@@ -116,22 -101,12 +119,21 @@@
     *defaults*.
  
     All option names used in interpolation will be passed through the
-    :meth:`optionxform` method just like any other option name reference.  For
-    example, using the default implementation of :meth:`optionxform` (which converts
-    option names to lower case), the values ``foo %(bar)s`` and ``foo %(BAR)s`` are
-    equivalent.
+    :meth:`optionxform` method just like any other option name reference.  Using
+    the default implementation of :meth:`optionxform`, the values ``foo %(bar)s``
+    and ``foo %(BAR)s`` are equivalent.
  
 +   .. versionadded:: 2.3
 +
 +   .. versionchanged:: 2.6
 +      *dict_type* was added.
 +
 +   .. versionchanged:: 2.7
 +      The default *dict_type* is :class:`collections.OrderedDict`.
 +      *allow_no_value* was added.
  
 -.. class:: SafeConfigParser([defaults[, dict_type]])
 +
 +.. class:: SafeConfigParser([defaults[, dict_type[, allow_no_value]]])
  
     Derived class of :class:`ConfigParser` that implements a more-sane variant of
     the magical interpolation feature.  This implementation is more predictable as