Add a modified patch from craigcitro@ to handle namespace sharing.

python/google/__init__.py

diff --git a/python/google/__init__.py b/python/google/__init__.py
index de40ea7..5585614 100755
--- a/python/google/__init__.py
+++ b/python/google/__init__.py
@@ -1 +1,4 @@
-__import__('pkg_resources').declare_namespace(__name__)
+try:
+  __import__('pkg_resources').declare_namespace(__name__)
+except ImportError:
+  __path__ = __import__('pkgutil').extend_path(__path__, __name__)

python/google/protobuf/__init__.py

diff --git a/python/google/protobuf/__init__.py b/python/google/protobuf/__init__.py
index 533821c..5d24419 100755
--- a/python/google/protobuf/__init__.py
+++ b/python/google/protobuf/__init__.py
@@ -31,3 +31,9 @@
 # Copyright 2007 Google Inc. All Rights Reserved.
 
 __version__ = '3.0.0b2'
+
+if __name__ != '__main__':
+  try:
+    __import__('pkg_resources').declare_namespace(__name__)
+  except ImportError:
+    __path__ = __import__('pkgutil').extend_path(__path__, __name__)

python/google/protobuf/pyext/__init__.py

diff --git a/python/google/protobuf/pyext/__init__.py b/python/google/protobuf/pyext/__init__.py
index e69de29..5585614 100644
--- a/python/google/protobuf/pyext/__init__.py
+++ b/python/google/protobuf/pyext/__init__.py
@@ -0,0 +1,4 @@
+try:
+  __import__('pkg_resources').declare_namespace(__name__)
+except ImportError:
+  __path__ = __import__('pkgutil').extend_path(__path__, __name__)