charmhub api return requested base in "revision-not-found" error response data

[Heather Lanigan]

Found with the juju bug: https://bugs.launchpad.net/juju/+bug/1975510

`juju download mysql-router --series impish --channel stable` is failing.

The equivalent curl is:

curl -s https://api.snapcraft.io/v2/charms/refresh -H 'Content-type: application/json' -d '{"context":[],"actions":[{"action":"install","instance-key":"d1708d3b-3101-4df9-87c6-9aa46651fd5d","name":"mysql-router","channel":"stable","base":{"architecture":"amd64","name":"ubuntu","channel":"21.10"}}],"fields":["bases","config-yaml","download","id","license","metadata-yaml","name","publisher","resources","revision","summary","type","version"]}'

Which returns the error: "code":"revision-not-found", "message":"No revision was found in the Store."

However, its extra.releases data includes:
            {
              "base": {
                "architecture": "amd64",
                "channel": "21.10",
                "name": "ubuntu"
              },
              "channel": "stable"
            },

Which is what was requested.