There is a bug with draft conflict when editing. Edit button is disabled when we have conflict with drafts from other users which suggest that we don't have permission to edit draft. But when we open link in new tab then we can edit and save selected draft.

Steps to reproduce:

1) Create content item and publish it e.g. blog post
2) Create new draft for published content item
3) Go to edit published content item as another user
4) In popup with drafts conflict button edit should be disabled
5) Right click on edit button and choose open link in new tab
6) Edit and save draft

I've tested it as administrator and editor users.