service: fix SerializedInvoker CallError handling.

This cutpaste needs refactored. Ensure the caller receives a copy of the
exception.

mitogen/service.py

@@ -271,9 +271,12 @@ class SerializedInvoker(Invoker):
             method_name, kwargs, msg = tup
             try:
                 super(SerializedInvoker, self).invoke(method_name, kwargs, msg)
+            except mitogen.core.CallError:
+                e = sys.exc_info()[1]
+                LOG.warning('%r: call error: %s: %s', self, msg, e)
+                msg.reply(e)
             except Exception:
-                LOG.exception('%r: while invoking %r of %r',
-                              self, method_name, self.service)
+                LOG.exception('%r: while invoking %s()', self, method_name)
                 msg.reply(mitogen.core.Message.dead())
 
     def invoke(self, method_name, kwargs, msg):