Unable to login to local docker-hosted in Chrome (works in Safari)

Created by: kevinseelbach

• Sourcegraph version: 3.13.2 , 3.13.1
• **Platform information: Docker version 19.03.5, build 633a0ea Chrome 80.0.3987.132 (also tested Brave browser, same issue there too) Safari Version 13.0.5 (15608.5.11) Catalina **

Steps to reproduce:

1. Run the server for self-hosted exactly as described in the steps
2. Try to create an account on the chrome site. Forms always fail. Set up the site admin in safari. Try logging in on chrome with site-admin user. Fails. Create a regular user in Site-admin on Safari and reset password. Paste reset-password link in Chrome and attempt to submit form with new password. Fails.

Expected behavior:

That at least something would work in Chrome.

Actual behavior:

Every form request to Chrome results in a 403 or 401.

Attached txt file is a Chrome HAR. Github does not allow uploading files with HAR extension. 127.0.0.1.txt