OpenMediaVault-4.0.15执行更新(apt update)时报错“TypeError: 'NoneType' object is not callable”

OpenMediaVault-4.0.15执行更新(apt update)时报错,详细错误信息如下：

命中:12 http://packages.openmediavault.org/public arrakis InRelease            
Exception ignored in: <function WeakValueDictionary.__init__.<locals>.remove at 0x7f7dc337b730>
Traceback (most recent call last):
  File "/usr/lib/python3.5/weakref.py", line 117, in remove
TypeError: 'NoneType' object is not callable
Exception ignored in: <function WeakValueDictionary.__init__.<locals>.remove at 0x7f7dc337b730>
Traceback (most recent call last):
  File "/usr/lib/python3.5/weakref.py", line 117, in remove
TypeError: 'NoneType' object is not callable

通过观察发现，只要从packages.openmediavault.org中下载文件失败，就会报告这个错误。

发生错误之后，重新执行

$ sudo apt update

即可解决这个问题，或者忽略这个错误信息即可。