Specify location of CHANGELOG file
### Summary
As a gitlab-ee user whose team only creates debian packages, it is impossible to specify the location (debian/changelog) for the changelog (available on the main repository page).
### Steps to reproduce
* Click "Add changelog"
* Change path to debian/changelog
* Click "Commmit changes"
Error: A file with this name already exists.
### Example Project
* https://salsa.debian.org/debian/devscripts does not have changelog configured because the file location is in "./debian"
* https://salsa.debian.org/debian/freetype has it configured because the changelog is in the root directory.
Other distributions using a hosted gitlab that could benefit from this feature:
* https://git.devuan.org
### What is the current *bug* behavior?
Error message appears, action is denied.
### What is the expected *correct* behavior?
No error message, location of changelog is saved.
### Relevant logs and/or screenshots
None
### Output of checks
None
#### Results of GitLab environment info
Not relevant
#### Results of GitLab application Check
Not relevant
### Possible fixes
No workaround found. What was tested: removing the file via git, adding changelog location via GUI, pulling code and restoring contents of file.
issue