Using "../config" as config_sync_directory causes errors

[joeparsons]

After installing a Drupal on a Pantheon site using a custom distribution that is using the scaffold files from this repo, I see the following error on the Drupal status report page:

Errors found: Configuration sync directory

The directory ../config does not exist.

As well as the following error in the Drupal watchdog logs:

Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your ../config
directory which contains the following lines:

# Deny all requests from Apache 2.4+.
<IfModule mod_authz_core.c>
  Require all denied
</IfModule>

# Deny all requests from Apache 2.0-2.2.
<IfModule !mod_authz_core.c>
  Deny from all
</IfModule>

# Turn off all options we don't need.
Options -Indexes -ExecCGI -Includes -MultiViews

# Set the catch-all handler to prevent scripts from being executed.
SetHandler Drupal_Security_Do_Not_Remove_See_SA_2006_006
<Files *>
  # Override the handler again if we're run later in the evaluation list.
  SetHandler Drupal_Security_Do_Not_Remove_See_SA_2013_003
</Files>

# If we know how to do it safely, disable the PHP engine entirely.
<IfModule mod_php7.c>
  php_flag engine off
</IfModule>