Turns out to be some code which tries to be clever about removing the

multipart envelope in LocalStore.java. It is thrown away if there is
just one item in the multipart. This breaks the display of attachment
only message, since the attachment is no longer detected by the code
which creates the view. I made a fix (see patch below) which checks if
the single item in the multipart is not a attachment.

        -- patch from wernermann29 at googlemail.com