workspaceFolder no longer accepts VS Code workspace files

[AngellusMortis]

• VSCode Version: 1.52.1
• Local OS Version: Arch Linux
• Remote OS Version: Debian Stretch I think? (remote OS should not matter, but it was the official Python 2.7 Docker container)
• Remote Extension/Connection Type: Docker

Steps to Reproduce:

1. Set workspaceFolder to the path for a VS Code .code-workspace file.
2. Add a postCreateCommand, postAttachCommand, or postStartCommand

Does this issue occur when you try this locally?: N/A
Does this issue occur when you try this locally and all extensions are disabled?: N/A

This started happening only with a newer version of VS Code (1.52 most likely, I cannot remember what version I was on before, but I usually update in a somewhat timely manner). Previously, if workspaceFolder was actually set to .code-workspace file, it would open the workspace after attaching VS Code, now it just does not work. It looks like it is because it is setting the -w option (working dir) on docker so now it actually must be a real directory. This was a nice hack to allow for multi-root workspaces inside of Docker containers. The only two folders we had in our workspace was the main app (/app) and a extra Docker Compose only mount for the Docker file (/docker) so the workspace was only to give easy access to the Docker files.

[chrmarti]

That must have worked by chance. We want to investigate opening a workspace using a devcontainer.json property in #3665.

What should work: Place a .devcontainer/devcontainer.json in the folder where the .code-workspace file is stored and make sure all workspace folders are contained in that same folder (possibly in subfolders). This only works if the .code-workspace file exists on the local filesystem.

Closing as duplicate of the above issue.