The Bug:

When using the directory type source and specifying a certain folder, all textures under the same folder name are stitched to the final atlas. This happens across all namespaces (including the default minecraft namespace) and all resource packs.

Steps to reproduce:

1. Download the resource packs attached.
2. Apply both resource packs.

Observed behavior:

From the log, another_custom:entity/bad_texture is stitched to the block atlas even when it is from another resource pack, causing miplevel to drop.

Expected behavior:

Only the entity folder of pack 1 is stitched.

Why it matters:

Suppose we have a lightweight resource pack (Pack A) and a massive resource pack (Pack B.) Both A and B share the same texture folder "custom", but Pack A uses this folder for item textures, while Pack B uses it for other reasons such as mod resources. Pack B texture would be stitched into the block atlas even though it is not used by block/item models, disrupting the atlas structure (such as the miplevel mentioned above.)