Fix half of testfsoids

In Python 2 str(SomeClass) returns "modulename.ClassName".

In Python 3 str(SomeClass) returns "<class 'modulename.ClassName'>".

We want the former.

src/ZODB/FileStorage/fsoids.py

@@ -193,6 +193,8 @@ class Tracer(object):
                                 ref2name[ref] = klass = get_class(r.data)
                     elif isinstance(klass, tuple):
                         ref2name[ref] = klass = "%s.%s" % klass
+                    else:
+                        klass = "%s.%s" % (klass.__module__, klass.__name__)
 
                     self._msg(oid, tid, "references", oid_repr(ref), klass,
                               "at", pos)