Default {MEDLEY} to DSK if Unix MEDLEYDIR doesn't have a host

[rmkaplan]

Make sure to pack {DSK} onto the value of (UNIX-GETENV "MEDLEYDIR") when setting up or resetting the {MEDLEY} pseudohost

[pamoroso]

On Linux Mint 22.1 Cinnamon the apps loadup fails with an error:

paolo@lispmachine:~/medley/medley$ gh pr checkout 2627
remote: Enumerating objects: 11, done.
remote: Counting objects: 100% (11/11), done.
remote: Compressing objects: 100% (7/7), done.
remote: Total 11 (delta 4), reused 10 (delta 4), pack-reused 0 (from 0)
Unpacking objects: 100% (11/11), 24.35 KiB | 1.52 MiB/s, done.
From github.com:Interlisp/medley
 * [new branch]        rmk191--Make-sure-MEDLEY-pseudohost-defaults-to-host-DSK -> origin/rmk191--Make-sure-MEDLEY-pseudohost-defaults-to-host-DSK
branch 'rmk191--Make-sure-MEDLEY-pseudohost-defaults-to-host-DSK' set up to track 'origin/rmk191--Make-sure-MEDLEY-pseudohost-defaults-to-host-DSK'.
Switched to a new branch 'rmk191--Make-sure-MEDLEY-pseudohost-defaults-to-host-DSK'
Checkout complete!
paolo@lispmachine:~/medley/medley$ git pull
remote: Enumerating objects: 1, done.
remote: Counting objects: 100% (1/1), done.
remote: Total 1 (delta 0), reused 1 (delta 0), pack-reused 0 (from 0)
Unpacking objects: 100% (1/1), 206 bytes | 206.00 KiB/s, done.
From github.com:Interlisp/medley
   406b509b..db8a7f4a  master                 -> origin/master
 * [new branch]        rmk190--Reset-MEDLEYDIR-on-restart -> origin/rmk190--Reset-MEDLEYDIR-on-restart
 * [new tag]           medley-260521-db8a7f4a -> medley-260521-db8a7f4a
Already up to date.
paolo@lispmachine:~/medley/medley$ git clean -d -f -x
Removing library/RDSYS
Removing library/RDSYS.LCOM
Removing loadups/
paolo@lispmachine:~/medley/medley$ ./scripts/loadup-all.sh -apps
>>>>> START loadup-init
"/home/paolo/bin/lde" "/home/paolo/medley/medley/internal/loadups/starter.sysout" -id "loadup_init_1" -title "Medley::loadup_init_1" -g 1024x768 -sc 1024x768 -noscroll
MEDLEYDIR: "/home/paolo/medley/medley"
LOGINDIR: "/home/paolo/medley/medley/loadups/build/logindir"
GREET FILE: "/home/paolo/medley/medley/loadups/build/loadup-init.init"
REM.CM FILE: ""
VMEM FILE: "/home/paolo/medley/medley/loadups/build/logindir/vmem/lisp_loadup_init_1.virtualmem"
----- FAILURE loadup-init-----
..... files created .....
<<<<< END loadup-init

----- loadup-all: FAILURE -----

The dribble files: loadups.zip