Fix find_globals to handle Python 2->3 module renamings

Stdlib's _compat_pickle is a big help here, but I've an uneasy feeling
it's not supposed to be a public API.

src/ZODB/broken.py

@@ -12,8 +12,6 @@
 #
 ##############################################################################
 """Broken object support
-
-$Id$
 """
 
 import sys
@@ -23,6 +21,13 @@ import zope.interface
 
 import ZODB.interfaces
 
+try:
+    # Python 3
+    import _compat_pickle
+except ImportError:
+    # Python 2
+    _compat_pickle = None
+
 broken_cache = {}
 
 @zope.interface.implementer(ZODB.interfaces.IBroken)
@@ -34,7 +39,7 @@ class Broken(object):
 
        Broken objects don't really do much of anything, except hold their
        state.   The Broken class is used as a base class for creating
-       classes in leu of missing classes::
+       classes in lieu of missing classes::
 
          >>> Atall = type('Atall', (Broken, ), {'__module__': 'not.there'})
 
@@ -145,6 +150,9 @@ def find_global(modulename, globalname,
          >>> find_global('sys', 'path') is sys.path
          True
 
+         >>> find_global('__builtin__', 'object') is object
+         True
+
        If an object can't be found, a broken class is returned::
 
          >>> broken = find_global('ZODB.not.there', 'atall')
@@ -188,6 +196,13 @@ def find_global(modulename, globalname,
          >>> broken_cache.clear()
        """
 
+    if _compat_pickle is not None:
+        if (modulename, globalname) in _compat_pickle.NAME_MAPPING:
+            modulename, globalname = _compat_pickle.NAME_MAPPING[
+                                            (modulename, globalname)]
+        if modulename in _compat_pickle.IMPORT_MAPPING:
+            modulename = _compat_pickle.IMPORT_MAPPING[modulename]
+
     # short circuit common case:
     try:
         return getattr(sys.modules[modulename], globalname)

src/ZODB/persistentclass.txt

@@ -273,7 +273,7 @@ If we copy an instance via export/import, the copy and the original
 share the same class:
 
     >>> file = connection.exportFile(p._p_oid)
-    >>> file.seek(0)
+    >>> _ = file.seek(0)
     >>> cp = connection.importFile(file)
     >>> file.close()
     >>> cp.color