Admin saving to _posts in root instead of custom collection folder collections_dir

[ADTC]

Description:

When editing posts which have been moved to the custom collections directory, as defined by collections_dir in _config.yml Admin deletes the file in the custom_collection_dir/_posts folder and creates it in the _posts folder (in root).

Tell us a bit about yourself:

• jekyll (4.3.2)
• jekyll-admin (0.11.1)
• Node v20.1.0
• macOS Ventura M1
• Firefox latest

Steps to reproduce:

1. Add the configuration to _config.yml for custom collection folder.
2. As per instruction, move the _posts folder in custom collection directory.
3. Reload bundle exec jekyll serve
4. Open admin and make any change in a post. Save the changes.
5. Check the result in the file structure (done best if you have a Git repo tracking changes).

I expected the following:

Changes should be saved to the custom collection directory.

But got the following, instead:

Changes saved to a new file (in a subfolder) in root directory, with the file in custom collection directory deleted.

Other details:

Related: #449