Yeah!  I have been thinking about this (as I convert the download bit over too)... This is ugly.

How about this?

```json
{
  "channel": "release",
   "branch": "latest"
}
```

```json
{
  "channel": "release",
   "branch": "17.0"
}
```

```json
{
  "channel": "prerelease",
   "branch": "aurora"
}
```

```json
{
  "channel": "tinderbox",
   "branch": "mozilla-central"
}
```