Mining Z-level gets generated over on load

[NataKilar]

Description of issue

Mining Z-level access areas (hallways and stairs) are generated over on load with cave generation.

Difference between expected and actual behavior

Mining areas set to ignore mining generation should not be generated over on load.

Steps to reproduce

Save the server, then load.

Length of time in which bug has been known to occur

Unknown, likely since Outreach map rework or #483