Mailcap problem specifying application/octet-stream

[John S Cooper <John.Cooper@eu.citrix.com>]

My .mailcap has the following line (I use Win2K):

application/octet-stream; shelex %s

(to let the OS launch programs based on their filename suffix.)

However, my mailcap-mime-data now has 2 entries for application/octet-stream:

My .mailcap stuff:

  ("octet-stream"
   (viewer . "shelex %s")
   (type . "application/octet-stream"))

.. and the default:

  ("octet-stream"
   (viewer . mailcap-save-binary-file)
   (non-viewer . t)
   (type . "application/octet-stream"))

When I hit RET on the MIME button, it seems the default action takes effect and
I'm prompted to save the attachment to a file.

It looks like mailcap-add-mailcap-entry might be keeping both entries because
the viewer is different in each case (although this is something of a guess!).

Any ideas on how I can make my .mailcap specification for
application/octet-stream override the default?

Thanks,

    --- John