!11000 reset exception listener

From: @kisnwang
Reviewed-by: @chujinjin,@wuxuejian
Signed-off-by: @wuxuejian

mindspore/ccsrc/backend/session/executor.cc

@@ -292,6 +292,7 @@ void Executor::RunTask(const std::shared_ptr<Task> &task, bool sync) {
       return finished;
     });
   }
+  ClearDoneTasks();
   MsException::Instance().CheckException();
 }
 

mindspore/core/ir/tensor.h

@@ -89,6 +89,7 @@ class WaitEvent : public ExceptionListener {
     }
     MsException::Instance().SetExceptionListener(const_cast<WaitEvent *>(this));
     cond_var_.wait(lock, [this] { return !need_wait_; });
+    MsException::Instance().SetExceptionListener(nullptr);
     MsException::Instance().CheckException();
   }