Docker attempts to create wp-config.php in /build

[pento]

Describe the bug

When running TestPress on a clean system, with a fresh checkout of WordPress, creation of the wp-config.php file will fail.

To Reproduce

Steps to reproduce the behaviour:

1. Check out a fresh copy of WordPress
2. Select that fresh copy as your WordPress directory in TestPress
3. Wait for Docker to restart with this new directory
4. See the debug message output, showing that wp-config.php wasn't created

Expected behaviour

wp-config.php should be created!