The file 'UPGRADE' says the following lines but the mentioned file is not there.
Upgrading from UseModWiki or old "phase 2" Wikipedia code
There is a semi-maintained UseModWiki to MediaWiki conversion script at
maintenance/importUseModWiki.php; it may require tweaking and customization
to work for you.
Install a new MediaWiki first, then use the conversion script which will
output SQL statements; direct these to a file and then run that into your
database.
You will have to rebuild the links tables etc after importing.
Version: unspecified
Severity: normal