Sinon does not check the contents of the passed error when checked via
sinon.stub().calledWith.
```
callback = sinon.stub()
callback(new Error("some message"))
.calledWith(new Error("completely different message"))
=== true
```
Cherry-pick plus an additional patch for the joinProject bail-out.
(cherry picked from commit d9570fee70701a5f431c39fdbec5f8bc5a7843fe)
Then, don't send new chat messages and new comments to those restricted clients.
We do this because we don't want to leak private information (email addresses
and names) to "restricted" users, those who have read-only access via a
shared token.
