runner: Runner update failed when running inside a docker container

Describe the bug I have a Github Actions runner program running inside a docker container. It ran well for a month until it got to update to a newer version.

To Reproduce Steps to reproduce the behavior:

1. Download docker runner v2.277.1 and configure it.
2. Use COPY to copy the docker runner into a docker image.
3. Run the docker container.
4. Wait for a new version(v2.278.0) and update.

Expected behavior The runner inside the docker container gets updated automatically without error.

Runner Version and Platform

Version of your runner? Original version is v2.277.1, updating to v2.278.0.

OS of the machine running the runner? OSX/Windows/Linux/… 18.04.1-Ubuntu

What’s not working?

Update fails with following output:

√ Connected to GitHub

2021-04-23 01:39:18Z: Listening for Jobs
Runner update in progress, do not shutdown runner.
Downloading 2.278.0 runner
An error occurred: Access to the path is denied.