vscode-with-extensions: invalid extension path when using VSCodium

[boi4]

When using https://nixos.wiki/wiki/VSCodium to install VSCodium with extensions, VSCodium is not able to start.
The reason behind this is, that the extension path in the wrapper is false and VSCode will try to create the extension directory in a read-only filesystem.

~ % cat $(which codium)
#! /nix/store/8gy2bmpz3qawxr3g8hqhfgkf32wb0wfl-bash-4.4-p23/bin/bash -e
exec "/nix/store/17f7f6psymqdv46nzim3z787aqj8bqsa-vscodium-1.42.1/bin/codium"  --extensions-dir /nix/store/bbri15rl2j5d3j0zxnplahwfl9nxdrvh-vscodium-extensions-1.42.1/share/vscodium/extensions "$@"
 ~ % ls /nix/store/bbri15rl2j5d3j0zxnplahwfl9nxdrvh-vscodium-extensions-1.42.1/share/                   
vscode

To Reproduce
Steps to reproduce the behavior:

1. Add content of https://nixos.wiki/wiki/VSCodium to configuration.nix
2. run the following:

~ % codium --verbose
Fontconfig warning: "/etc/fonts/fonts.conf", line 86: unknown element "blank"
[29214:0308/124529.045951:ERROR:sandbox_linux.cc(369)] InitializeSandbox() called with multiple threads in process gpu-process.
[main 2020-03-08T11:45:29.058Z] Error: ENOENT: no such file or directory, mkdir
[main 2020-03-08T11:45:29.060Z] Lifecycle#kill()

Expected behavior
VSCodium should start and load the right extensions.

.

Metadata

• system: "x86_64-linux"
• host os: Linux 5.5.7, NixOS, 20.09pre215947.82b54d49066 (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.3
• channels(f): "nixo-19.09pre180443.4dd5c93998d"
• channels(root): "nixos-20.09pre215947.82b54d49066"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
 - pkgs.vscode-with-extensions

[veprbl]

Supposed to be fixed on master with #71251

[boi4]

Yes, you are right. My bad.