Frontport bug fixes in ConflictResolution to the trunk.

The main idea in the bug fix is to recover more gracefully when
something goes wrong trying to load classes for conflict resolution.

XXX This accidentally got checked in on the Zope 2.5 branch first.

src/ZODB/ConflictResolution.py

@@ -15,6 +15,7 @@ from cStringIO import StringIO
 from cPickle import Unpickler, Pickler
 
 from ZODB.POSException import ConflictError
+import zLOG
 
 bad_classes = {}
 
@@ -70,20 +71,29 @@ def persistent_id(object):
         return None
     return object.data
 
+def load_class(class_tuple):
+    try:
+        klass = _classFactory(class_tuple[0], class_tuple[1])
+    except (ImportError, AttributeError):
+        zLOG.LOG("Conflict Resolution", zLOG.BLATHER,
+                 "Unable to load class", error=sys.exc_info())
+        bad_class[class_tuple] = 1
+        return None
+    return klass
+
 def tryToResolveConflict(self, oid, committedSerial, oldSerial, newpickle,
                          committedData=''):
-    #class_tuple, old, committed, newstate = ('',''), 0, 0, 0
+    # class_tuple, old, committed, newstate = ('',''), 0, 0, 0
     try:
+        prfactory = PersistentReferenceFactory()
         file = StringIO(newpickle)
         unpickler = Unpickler(file)
-        prfactory = PersistentReferenceFactory()
         unpickler.persistent_load = prfactory.persistent_load
         class_tuple = unpickler.load()[0]
         if bad_class(class_tuple):
             return 0
-
         newstate = unpickler.load()
-        klass = _classFactory(class_tuple[0], class_tuple[1])
+        klass = load_class(class_tuple)
         inst = klass.__basicnew__()
 
         try: