[ic] admin login not sending mv_arg to destination page

[Caleb Groom]

In several custom reports that I have written (outside of IC) I link
directly into the IC Admin pages so that I don't have to reinvent the
wheel.  I've found a minor quirk when the user is not already logged
into the admin section and tries to access the order_view.html page.

Basically, admin/login.html is not preserving the mv_arg value it
received from the referring page and passing it along.

Here's a short demonstration:

1. Log into the admin section and browse to the following URL:
http://foo.com/cgi-bin/foo/admin/order_view.html?mv_arg=ORDERNUMBER (s//
where needed).  You will be taken to the 'Order manager: View order'
page.  
2. Logout.
3. Browse to the above URL.  You will be taken to admin/login.html as
expected.
4. Login.  You will be bounced to 'Orders: Pending Orders' page rather
than the view order page as desired.

My fix is simple but because I am not aware of all of the implications
of mv_arg it should really be looked over who knows this stuff a lot
better that I.

I'm running 4.9.8 but I checked 4.9.9 and the dev CVS and they look the
same.  Here's the diff to CVS:

--- login.html.original 2003-11-17 16:09:50.000000000 -0600
+++ login.html  2003-11-17 16:10:23.000000000 -0600
@@ -43,6 +43,7 @@
 <INPUT TYPE=hidden NAME=mv_nextpage VALUE="[either][cgi
destination][or]__UI_BASE__/index[/either]">
 <INPUT TYPE=hidden NAME=destination VALUE="[cgi destination]">
 <INPUT TYPE=hidden NAME=mv_doit  VALUE=return>
+<INPUT TYPE=hidden NAME=mv_arg VALUE="[value mv_arg]">