LFS downloads redirected to GCS does not set Content-Disposition

Summary

Downloads of LFS objects saved in Google Cloud Storage are saved by the browser with the hash as filename.

Steps to reproduce

• Setup a instance with GCS as LFS store.
• Upload files.
• Download files via web interface, the browser will ask file to be saved as "442e0c76ffb0b850e70f6889a7f4df77272daa6269691671912a1c4fb96c".

Example Project

https://salsa-test.debian.net/waldi/test-lfs/blob/master/linux_4.17.8-1.dsc

What is the current bug behavior?

Redirects to GCS don't include a response-content-disposition parameter. There is code to generate some, but it seems to be not always done.

What is the expected correct behavior?

Redirects to GCS should always include a response-content-disposition parameter and provide the browser with a name to save the file under.

Output of checks

(If you are reporting a bug on GitLab.com, write: This bug happens on GitLab.com)

Results of GitLab environment info

Expand for output related to GitLab environment info

System information
System:         Debian 9.5
Current User:   git
Using RVM:      no
Ruby Version:   2.3.3p222
Gem Version:    2.5.2.1
Bundler Version:1.13.6
Rake Version:   12.3.1
Redis Version:  3.2.6
Git Version:    2.11.0
Sidekiq Version:5.1.3
Go Version:     go1.10.3 linux/amd64
GitLab information
Version:        11.1.2
Revision:       50bae62c38
Directory:      /srv/salsa-test.debian.net/gitlab
DB Adapter:     postgresql
URL:            https://salsa-test.debian.net
HTTP Clone URL: https://salsa-test.debian.net/some-group/some-project.git
SSH Clone URL:  git@salsa-test.debian.net:some-group/some-project.git
Using LDAP:     no
Using Omniauth: no
GitLab Shell
Version:        7.1.4
Repository storage paths:

• default: /srv/salsa-test.debian.net/repositories Hooks: /srv/salsa-test.debian.net/gitlab-shell/hooks Git: /usr/bin/git

Possible fixes

(If you can, link to the line of code that might be responsible for the problem)