Update background source for history

js/id/connection.js

@@ -108,7 +108,7 @@ iD.Connection = function() {
                 method: 'PUT',
                 path: '/api/0.6/changeset/create',
                 options: { header: { 'Content-Type': 'text/xml' } },
-                content: iD.format.XML.changeset(comment)
+                content: iD.format.XML.changeset(comment, imagery_used)
             }, function (err, changeset_id) {
                 if (err) return callback(err);
                 oauth.xhr({

js/id/graph/history.js

@@ -1,5 +1,6 @@
 iD.History = function() {
-    var stack, index, imagery_used,
+    var stack, index,
+        imagery_used = 'Bing',
         dispatch = d3.dispatch('change');
 
     function perform(actions) {
@@ -16,8 +17,6 @@ iD.History = function() {
             graph = actions[i](graph);
         }
 
-        imagery_used = 'Bing'; // TODO, un-hardcode
-
         return {graph: graph, annotation: annotation, imagery_used: imagery_used};
     }
 
@@ -111,7 +110,10 @@ iD.History = function() {
         },
 
         imagery_used: function(source) {
-            return _.unique(_.pluck(stack.slice(1, index + 1), 'imagery_used'));
+            if (source) imagery_used = source;
+            else return _.without(
+                    _.unique(_.pluck(stack.slice(1, index + 1), 'imagery_used')),
+                    undefined, 'Custom');
         },
 
         reset: function () {

js/id/ui/layerswitcher.js

@@ -126,6 +126,7 @@ iD.layerswitcher = function(map) {
                             d.name = 'Custom (configured)';
                         }
                         map.background.source(d.source);
+                        map.history().imagery_used(d.name);
                         map.redraw();
                         selectLayer(d);
                     })