LXC容器：mktemp：无法通过模板创建文件

在一个新的容器上，我做：

lxc-attach -n mycontainer -- apt-get install -y wget

但是，wget的安装部分失败，并显示以下消息

...
Processing triggers for ca-certificates (20160104) ...
mktemp: failed to create file via template ‘/some/path/on/host/machine’: No such file or directory
dpkg: error processing package ca-certificates (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 ca-certificates

解决方案只是清除环境变量，如下所示：

lxc-attach --clear-env -n mycontainer -- apt-get install -y wget

来自lxc-attach --help：

  --clear-env   Clear all environment variables before attaching.
                The attached shell/program will start with only
                container=lxc set.
  --keep-env    Keep all current environment variables. This
                is the current default behaviour, but is likely to
                change in the future.