a8n/auth: Regex search/replace doesn't work in private repos

Created by: mrnugget

In order to reproduce, make sure that you have two external services:

1. GitHub external service with your token that clones github.com/sourcegraph/automation-testing, a public repo
2. GitHub external service with sd9 token (see 1Password) that clones github.com/sd9/ava

Preview a CampaignPlan for automation-testing repo with these parameters:

{"scopeQuery": "repo:github.com/sourcegraph/automation-testing","regexpMatch": "This", "textReplace": "That"}

(Click here to run this in local API console)

That returns a few results.

Now, if I change the scopeQuery to search github.com/sd9/ava it doesn't return anything:

{"scopeQuery": "repo:github.com/sd9/ava","regexpMatch": "This", "textReplace": "That"}

(Click here to run this in local API console)

But if I run the search manually, by searching for repo:github.com/sd9/ava This in regexp-mode), I get results.

Just not in Automation, which in combination with https://github.com/sourcegraph/sourcegraph/issues/7912 makes me think that this has something to do with auth