DOC: add pickle compat warning to docs

Author: jreback

doc/source/conf.py

@@ -248,7 +248,7 @@
                      'wiki ')}
 
 # remove the docstring of the flags attribute (inherited from numpy ndarray)
-# because these give doc build errors (see GH issue 5331) 
+# because these give doc build errors (see GH issue 5331)
 def remove_flags_docstring(app, what, name, obj, options, lines):
     if what == "attribute" and name.endswith(".flags"):
         del lines[:]

doc/source/io.rst

@@ -1967,9 +1967,16 @@ any pickled pandas object (or any other pickled object) from file:
 
    See: http://docs.python.org/2.7/library/pickle.html
 
+.. warning::
+
+   In 0.13, pickle preserves compatibility with pickles created prior to 0.13. These must
+   be read with ``pd.read_pickle``, rather than the default python ``pickle.load``.
+   See `this question <http://stackoverflow.com/questions/20444593/pandas-compiled-from-source-default-pickle-behavior-changed>`__
+   for a detailed explanation.
+
 .. note::
 
-    These methods were previously ``save`` and ``load``, prior to 0.12.0, and are now deprecated.
+    These methods were previously ``pd.save`` and ``pd.load``, prior to 0.12.0, and are now deprecated.
 
 .. _io.msgpack:
 

doc/source/v0.13.0.txt

@@ -1,7 +1,7 @@
 .. _whatsnew_0130:
 
-v0.13.0 (October ??, 2013)
---------------------------
+v0.13.0 (December ??, 2013)
+---------------------------
 
 This is a major release from 0.12.0 and includes a number of API changes, several new features and
 enhancements along with a large number of bug fixes.
@@ -817,6 +817,7 @@ Experimental
      As of 10/10/13, there is a bug in Google's API preventing result sets
      from being larger than 100,000 rows. A patch is scheduled for the week of
      10/14/13.
+
 .. _whatsnew_0130.refactoring:
 
 Internal Refactoring
@@ -860,6 +861,8 @@ to unify methods and behaviors. Series formerly subclassed directly from
 
    - ``Series(0.5)`` would previously return the scalar ``0.5``, instead this will return a 1-element ``Series``
 
+- Pickle compatibility is preserved for pickles created prior to 0.13. These must be unpickled with ``pd.read_pickle``, see :ref:`Pickling<io.pickle>`.
+
 - Refactor of series.py/frame.py/panel.py to move common code to generic.py
 
   - added ``_setup_axes`` to created generic NDFrame structures