Clicking "Done" on the Resource Packs screen causes a freeze even when there is no change

This issue was fixed in the pre-resource-pack era but has been reintroduced since then and I can't find the original issue.

Steps to reproduce:
1. Go to Options -> Resource Packs
2. Click "Done"

Expected result:
I'm taken straight back to the main menu.

Actual result:
The game freezes for a few seconds, it appears to reload the already active resource pack(s).