updateLookup has nasty edge cases

[mixmix]

in lookup.js

  function updateLookup(msg) {
    const { type, subfeed, metafeed } = msg.value.content

    // Update roots
    if (!detailsLookup.has(metafeed)) {

      // !detailsLookup.has(metafeed) !== "metafeed is a root)
      // this assumes that we have replicated the metafeed tree in the order
      // that it was created.

Need to watch for this being a problem if we do any fancy out of order replication