Ubuntu系统因etckeeper组件无法完成升级的问题求助

大家好，我在给Ubuntu系统做升级的时候碰到了etckeeper相关的报错，导致升级流程没法正常走完，具体的错误信息如下：

The operating system fails to make the proper updates:

/etc/etckeeper/unclean.d/README: 1: Files: not found
/etc/etckeeper/unclean.d/README: 2: uncommitted: not found
/etc/etckeeper/pre-install.d/README: 1: Files: not found
/etc/etckeeper/pre-install.d/README: 2: etc.: not found
/etc/etckeeper/pre-install.d/README: 3: uncommitted: not found
E: Problem executing scripts DPkg::Pre-Invoke 'if [ -x /usr/bin/etckeeper ]; then etckeeper pre-install; fi'
E: Sub-process returned an error code

这里要补充说明下：报错里提示“找不到”的那些文件其实都是存在的，我把这两个README的内容贴出来给大家参考：

• 1. /etc/etckeeper/unclean.d/README：
  Files in this directory are used to test if the working copy has uncommitted changes.

• 2. /etc/etckeeper/pre-install.d/README：
  Files in this directory are run before packages are installed, upgraded, etc. This is mostly used for sanity checks, ie, does /etc have any uncommitted changes?

有没有大佬能帮忙分析下这个问题，看看该怎么调整才能正常完成系统升级呀？

备注：内容来源于stack exchange，提问作者seomiotico