Commit redirects to MR form when "Create a merge request for this change" isn't selected
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### Summary
Commits from the UI for changes originating from a protected branch a user does not have push permissions to redirects to a new MR page. This occurs even when "Create a merge request for this change" is not selected.
### Steps to reproduce
1. In a project, under **Settings \> Repository \> Protected Branches** edit the rules for a branch to not allow users to push and merge.
2. From the protected branch, edit a file.
3. Commit the changes. In the window, deselect "Create a merge request for this change".
Note: in the window, a new branch will be created since the user does not have permission to push to the branch.
4. Result: User is redirect to the page to create a new MR.
Cancelling out of the MR redirects to the repository where the branch / commit exist.
This does not happen while editing from the IDE.
### Example Project
https://gitlab.com/irisb_ultimate_group/work/tickets/600820/project-a
### What is the current _bug_ behavior?
User is redirected to create a new merge request despite de-selecting "Create a merge request for this change"
### What is the expected _correct_ behavior?
Changes are committed to a new branch without being redirected to create a merge request.
### Output of checks
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This bug happens on GitLab.com
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