application/octet-stream and empty fileinputs

I noticed that if you submit an HTML::Form that it doesn't set the
content-type for empty fileinputs to application/octet-stream.  I am not
sure if this is legal or not.  I compared dumps of firefox vs. LWP and it
looks like firefox does set the content-type even if you don't have anything
for the input stream.  I suppose since the content is empty you *SHOULDN'T*
have to set a content-type, but I am curious to hear opinions on whether
this should be changed.

thanks,
eric