Bug 1677

This bug has been reported against nautilus, please look
http://bugzilla.gnome.org/show_bug.cgi?id=123744 to get the details.

according to the original bug report:
"mime-type should be: application/x-autopackage

I won't attach a whole .package, they can be big - here's a link to the
AutoPackage downloads page: http://autopackage.org/downloads.html

You can install any of those by just downloading and running them once, that'll
install the AutoPackage support code.  Doing so also registers the MIME handlers
for .package files.  You can then observe how Nautilus will ignore the MIME type
(handle it as a shell script) while gnome-open will work just fine (using
gnome-vfs).

The beginning of the script looks something like:
#!/bin/bash
# autopackage 0.6
# RootName @inkscape.org/inkscape:0.39cvs
# SoftwareVersion 0.39cvs
# InterfaceVersion
# PackageVersion

Perhaps checking for "#/bin/bash\n# autopackage " at the start of the file would
work."