MR with 0 conflicts not allowed to merge
## Summary
I have one merge request that ended up in a merge conflict situation due to some other merged code in master. After pushing a new rebased commit I have a merge request that can not be merged, but it is marked as conflicting with 0 conflicts.
## Steps to reproduce
The steps that got to this situation were:
- Create a new MR from branch in fork to forked repository in master branch without conflicts.
- Forked repository master branch changed and ended in a conflicting MR
- Merged the changes from forked repos in fork repo:
```
git checkout master
git fetch upstream master
git merge upstream/master
```
- Rebased branch on new master:
```
git checkout branch1
git rebase -i master
```
- Pushed updates to gitlab fork repository:
```
git push -f
```
- MR was updated with the new commit, but merge still not allowed and showing 0 conflicts.
## Expected behavior
MR should not be marked as conflicting when the conflicts number is 0
## Relevant logs and/or screenshots

but it is marked as conflicting with 0 conflicts

issue