Though I'm not sure exactly which maintenance scripts recreate the cache, dumpBackup.php definitely does.

Many environments run backups as a user other than the web user. When the backups run, the cache file can be recreated with invalid ownership and permissions.

This issue can be worked around by disabling the cache for maintenance scripts:

if ( $wgCommandLineMode ) { $wgCacheDirectory = false; }

However, it would be optimal for the maintenance scripts to not have this behavior.

Version: 1.16.x
Severity: major