Poor UX with "Create commit" button on non-open MR without any changes

Summary

A user would see "Create commit" button even on the merged non-open MR without any changes.

Steps to reproduce

(How one can reproduce the issue - this is very important)

What is the current bug behavior?

A user is seeing "Create commit" button even on the merged non-open MR without any changes.

See gitlab-com/www-gitlab-com!10766 (diffs)

screenshots on 2021-04-16 (3 years after the issue creation)

screenshots on 2018-04-21

What is the expected correct behavior?

A user should not see "Create commit" button on the merged non-open MR without any changes.

Relevant logs and/or screenshots

See the above.

Output of checks

This bug happens on GitLab.com (10.7.0-rc7-ee, and EE 13.11-pre).

Possible fixes

Hide the button in case of the~~merged~~ non-open MR without any changes.