Merge branch 'user-select-unassigned' into 'master'

Don't show Unassigned in user select when searching.

Fixes #2056.

When a search term is present, the Unassigned item isn't rendered, so the highlighted item is the first search result and hitting Enter works as expected.

See merge request !1620

app/assets/javascripts/project_users_select.js.coffee

@@ -11,6 +11,7 @@ class @ProjectUsersSelect
           Api.projectUsers project_id, query.term, (users) ->
             data = { results: users }
 
+            if query.term.length == 0
               nullUser = {
                 name: 'Unassigned',
                 avatar: null,