Redirected to help page when repo url starts with "help"

Created by: ecsgg

• Sourcegraph version: 3.22.0
• Platform information: Any

Steps to reproduce:

1. Have a repository URL that starts with "help". Example: "helpdesk.repo.com" or "helper.repo.com"
2. Go directly (or refresh the page) to any sourcegraph url that includes the repository url

Expected behavior:

You go to the linked sourcegraph page

Actual behavior:

You get redirected to https://docs.sourcegraph.com/@v3.22.0/desk.repo.com or https://docs.sourcegraph.com/@v3.22.0/er.repo.com