Custom theme overrides not working on `beta` releases

[codealchemy]

Describe the bug

When updating an existing app (using Rails 6 / Sprockets / asset pipeline), to 3.0.0.beta2 - custom theme overrides (following theming docs, which worked on 2.x.x releases) are not being picked up.

Specifically, anything defined in a projects app/assets/stylesheets/rails_admin/custom/theming.scss does not take precedence over RailsAdmin defaults (seems to be a load order issue for imports) .

Unsure if this applies to apps not using sprockets.

This can be reproduced on the dummy_app for the current master (see below)

Reproduction steps

Repro using the dummy_app in RailsAdmin -> codealchemy@1c8886f

Expected behavior

Existing theme overrides will continue to work (between 2.x.x and 3.x.x releases using the asset pipeline) as described in the Wiki.

Additional context

sassc-rails - 2.1.2
sassc - 2.4.0
sprockets - 4.0.2
rails - 6.1.3.1 (also seen on 6.0 project)
rails_admin - 3.x beta releases

[mshibuya]

This was caused because when sassc tries to resolve imports, files available by relative path take precedence over files in asset_paths.
In #3414 RailsAdmin CSS was moved to app/assets/stylesheet/rails_admin.scss, so @import "rails_admin/custom/theming"; picked app/assets/stylesheet/rails_admin/custom/theming.scss, which was directly accessible by the relative path.

Moving the CSS to app/assets/stylesheet/rails_admin/application.scss solved the issue.

[codealchemy]

Thanks!