The `merge_status` attribute can indicate the MR can be merged when no automatic merge is possible
The state machine
MergeRequest#merge_status doesn't take all properties into account:
MergeRequest#check_if_can_be_merged only checks for conflicts between it's HEAD and the target branch. But even when there are no conflicts, it's possible that the merge request cannot be merged automatically.
This is causing confusion because this attribute is exposed in the API.
I think we need to update the check so it takes all properties used in
MergeRequest#mergeable? into account, meaning:
Brought up in https://gitlab.zendesk.com/agent/tickets/81012 (Internal only)