Some path assets under NPM group repo become invisible by changing the group member order

SYMPTOM:

Changing group member order changes what users can see in the Browse page for NPM group repository.

REPRODUCE STEPS:

1. Create npm-proxy, npm-hosted, npm-group
2. Download something via npm-proxy, for example, lodash-4.17.19.tgz
3. Upload the downloaded asset into npm-hosted.
4. Check the npm-group repo, and it shows "lodash" directory and lodash-4.17.19.tgz file
5. From Browse, go to the npm-proxy repo and delete lodash-4.17.19.tgz asset (not "lodash" directory)
6. From the npm-group repository setting, make "npm-proxy" first.
7. Browse npm-hosted and check lodash-4.17.19.tgz is visible.
8. Browse npm-group, and you can't see any lodash-4.17.19.tgz which should exist under npm-hosted.

As of this typing, there is no easy workaround to delete this orphaned metadata asset from npm-proxy repository.

EXPECTED BEHAVIOUR:

The npm group repository should show correct contents under Browse regardless of the group member order.