19.03 XMonad and Plasma5 when launched from SDDM results in both launching even when only select XMonad

[CMCDragonkai]

Issue description

Testing on 19.03, when sddm and xmonad and plasma5 is installed. SDDM presents options on the bottom left none + xmonad, plasma5 + xmonad or plasma5 + none.

When selecting none + xmonad, xmonad is launched, but then KDE plasma5 launches at the same time as if you had selected plasma5 + xmonad. Note that selecting plasma5 only does also launch xmonad.

This behaviour is not consistent with 18.09.

Technical details

Please run nix-shell -p nix-info --run "nix-info -m" and paste the
results.

 - system: `"x86_64-linux"`
 - host os: `Linux 4.19.31, Formbay ML 2 A, noversion`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.2`
 - channels(root): `""`
 - nixpkgs: `/etc/nixos/nixpkgs`

It's running on nixpkgs: 23fd139

[stale]

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