URL mismatch with Sourcegraph extension

Created by: donavonelli

• Sourcegraph version: N/A
• Platform information: Sourcegraph extension

Steps to reproduce:

1. user installs the extension
2. user goes to set up the extension, sees that it wants the sourcegraph url
3. user types in https://sourcegraph.example.com
4. user gets redirected silently to https://sourcegraph.example.com/search
5. user copies https://sourcegraph.example.com/search and pastes it into sourcegraph extension
6. extension shows green checkmark; happy days
7. user clicks “find references” on something
8. generated URL includes /search where it should not
9. user gets an error message about “no repo found” because the URL translated into repo:^search/something because of the extra prefix.

Expected behavior: Sourcegraph extension works when given the URL it redirects to

Actual behavior: It doesn't work as intended