Last modified: 2009-08-02 13:37:55 UTC
The forceeditsummary option conflicts with a &nosummary=1 in URL. You will get MediaWiki:Missingcommentheader, but you cannot and should not giving any comment. Please also see bug 17416 for issue with forceeditsummary and &summary= in URL. Thanks.
$allowBlankSummary in EditPage.php must set to true, if nosummary is in the request.
fixed in r54206.