client: fix handling of unresolved conflicts on old and recent ZODB

neo/client/app.py

@@ -637,10 +637,15 @@ class Application(object):
                     # A later serial has already been resolved, skip.
                     resolved_serial_set.update(conflict_serial_set)
                     continue
+                # BBB: On ZODB < 3.10, tryToResolveConflict returns None
+                #      instead of raising ConflictError.
+                try:
                     new_data = tryToResolveConflict(oid, conflict_serial,
                         serial, data)
+                except ConflictError:
+                    new_data = None
                 if new_data is not None:
-                    logging.info('Conflict resolution succeed for '
+                    logging.info('Conflict resolution succeeded for '
                         '%r:%r with %r', dump(oid), dump(serial),
                         dump(conflict_serial))
                     # Mark this conflict as resolved
@@ -655,7 +660,7 @@ class Application(object):
                     logging.info('Conflict resolution failed for '
                         '%r:%r with %r', dump(oid), dump(serial),
                         dump(conflict_serial))
-            raise ConflictError(oid=oid, serials=(txn_context['ttid'],
+            raise ConflictError(oid=oid, serials=(conflict_serial,
                 serial), data=data)
         return result