Apache2::Upload ->upload method dies silently if any file field is empty

I am seeing some very suprising behavior with calling ->upload on a 
Apache2::Request object (with use Apache2::Upload). It appears that if 
the user did not click and select a file to upload, that is to say left 
the <input type="file" ...> field empty, the server stops processing the 
perl code and immediately sends a response to the browser with whatever 
it has so far. No error message appears in the error log.

It appears that this happens if *any* file field is left un-filled, that 
is to say, ->upload("file1") will silently die even if file1 was 
specified, if file2 was left un-filled.

I have written up a description and replication code here:

http://back.nber.org/sys-admin/apache2_upload_bug.html

Is this something anyone else has seen?

Thanks,

  - Alex Aminoff

    NBER