There needs to be the same number of place-holders as there are replacements.
Fixes an issue introduced in r1453239.
Identified by FindBugs running against the Tomcat code base (which has a package renamed copy of FileUpload).

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/fileupload/trunk@1458220 13f79535-47bb-0310-9956-ffa450edef68