Broken sign-in redirect when trying to download zip of private repo

Consider the url:
https://gitlab.com/neiljackson1984/ec-18-038_vintage_at_vancouver/-/archive/5aaceb4745c1900fa40fddae048078b7fc98a308/ec-18-038_vintage_at_vancouver-5aaceb4745c1900fa40fddae048078b7fc98a308.zip .

This url refers to the zip archive of particular commit of a project. The project is private. If I happen to be logged into GitLab when I navigate to the above url, the zip file downloads, just as expected.

In the case where I am not logged into GitLab, when I navigate to the above url, I expect to be redireced to the GitLab sign-in page, where, upon entering my credentials and clicking “Sign In”, the download of the zip file will commence. However, what actually happens is that, when I navigate to the above url, my browser is redirected to https://gitlab.com/users/sign_in.zip, and then I see a 404 error page from GitLab.

This behavior seems to be a bug rather than the intended behavior. Why is this happening?

My goal is to be able to generate a download url for the zip archive of a particular commit of a particular project. I want to be able to send the url to another GitLab user who has permission to access the project. When this other user navigates to the url, if he happens not to be logged into GitLab, I want him to be redirected to the sign-in page, and then, upon a successful sign-in, have the download of the zip file commence. A URL like the one above would seem to be a likely candidate for achieving my goal, but the sign-in redirect bug that I described above throws a wrench in the works. Is there some other way of achieving my goal?