I was trying to see if Bug #23694 still existed for 1.17 (since it has apparently resurfaced in svn) so I ran 1.17 web installer twice against the same database without creating a LocalSettings.php file. The second time through, it didn't properly sense the database schema but gave the following error
Warning: you requested the binary schema, but the existing database has the
mysql4 schema.
Version: 1.17.x
Severity: normal