missing required parameter: 'user'

[nickdesaulniers]

on a 1.4 device, navigator.mozId.request fails after signing in. The persona window stays open but contains a JSON response

{
  "success": false,
  "reason": "missing required parameter: 'user'"
}

I don't see anything in the docs for this, but maybe something should be added?

[callahad]

Suspect related to #4144