Allow multi fetch request parameter to contain only versioned entries

app/controllers/api/elements_controller.rb

@@ -4,12 +4,14 @@ class ElementsController < ApiController
     def index
       raise OSM::APIBadUserInput, "The parameter #{controller_name} is required, and must be of the form #{controller_name}=ID[vVER][,ID[vVER][,ID[vVER]...]]" unless params[controller_name]
 
-      id_ver_strings, id_strings = params[controller_name].split(",").partition { |iv| iv.include? "v" }
+      search_strings = params[controller_name].split(",")
+
+      raise OSM::APIBadUserInput, "No #{controller_name} were given to search for" if search_strings.empty?
+
+      id_ver_strings, id_strings = search_strings.partition { |iv| iv.include? "v" }
       id_vers = id_ver_strings.map { |iv| iv.split("v", 2).map(&:to_i) }
       ids = id_strings.map(&:to_i)
 
-      raise OSM::APIBadUserInput, "No #{controller_name} were given to search for" if ids.empty?
-
       current_model = controller_name.classify.constantize
       result = current_model.find(ids)
       unless id_vers.empty?

test/controllers/api/nodes_controller_test.rb

@@ -494,6 +494,15 @@ def test_index_with_versions
       node1 = create(:node)
       node2 = create(:node, :with_history, :version => 2)
 
+      # test a working call only with versions
+      get nodes_path(:nodes => "#{node2.id}v1,#{node2.id}v2")
+      assert_response :success
+      assert_select "osm" do
+        assert_select "node", :count => 2
+        assert_select "node[id='#{node2.id}'][version='1']", :count => 1
+        assert_select "node[id='#{node2.id}'][version='2']", :count => 1
+      end
+
       # test a working call
       get nodes_path(:nodes => "#{node1.id},#{node2.id}v1,#{node2.id}v2")
       assert_response :success