When building the x86_64 linux image (from the BuildStream Examples repo https://gitlab.com/BuildStream/buildstream-examples/tree/master/build-x86image), our base system requires importing a docker image. When trying to build this image we find that as a normal user, we are unable to copy files from the docker image into the sandbox, thus we get the following error message: ``` [--:--:--][][] START Checking sources [00:00:00][][] SUCCESS Checking sources [--:--:--][4d984a9d][build:base.bst ] START test-image/base/4d984a9d-build.5625.log [--:--:--][4d984a9d][build:base.bst ] START Staging sources [00:00:07][4d984a9d][build:base.bst ] FAILURE Staging sources [00:00:07][4d984a9d][build:base.bst ] FAILURE docker source at base.bst [line 5 column 2]: Error staging source: [Errno 13] Permission denied: '/home/jamesennis/.cache/buildstream/build/base-lkh0d0id/root/input/sbin/blkid' Sandbox directory: /home/jamesennis/.cache/buildstream/build/base-lkh0d0id ```