TNL-328 Cohort/server display auto

[TNL-180](https://openedx.atlassian.net/browse/TNL-180)

i know it's kind of out of scope for the story as defined, but it seems smelly to have this one function's signature with a slight but important difference from the rest.  would it require a lot of changes (to tests, e.g.) to apply the same changes to the others?