Bad browser behaviour?

Hi all
  
we're seeing some (IMO) undesirable behaviour for all tested current 
browsers (we tested FF, Chrome, IE and Opera).
  
It relates to abortive closes on chunked transfers.  In this case, I'm 
talking about a server close prior to the final 0 chunk.
  
All the browsers we tested ignore this and display the content with no 
warning whatsoever.
  
For our proxy to treat it as an abortive close is therefore a problem 
in our customers' eyes.
  
So what's the deal?  Should we allow this behaviour in the spec?  Or 
should browser vendors be encouraged to break the page / download?
  
Isn't it a potential security issue?

Adrien