Don't let window.location changes happen during draw modes

(closes #3996)

modules/behavior/draw_way.js

@@ -125,8 +125,15 @@ export function behaviorDrawWay(context, wayId, index, mode, startGraph) {
 
 
     drawWay.off = function(surface) {
-        context.pop(tempEdits);
-        tempEdits = 0;
+        // Drawing was interrupted unexpectedly.
+        // This can happen if the user changes modes,
+        // clicks geolocate button, a hashchange event occurs, etc.
+        if (tempEdits) {
+            context.pop(tempEdits);
+            while (context.graph() !== startGraph) {
+                context.pop();
+            }
+        }
 
         context.map()
             .on('drawn.draw', null);
@@ -268,7 +275,7 @@ export function behaviorDrawWay(context, wayId, index, mode, startGraph) {
         tempEdits = 0;
 
         var way = context.hasEntity(wayId);
-        if (!way || origWay.isDegenerate()) {
+        if (!way || way.isDegenerate()) {
             drawWay.cancel();
             return;
         }

modules/behavior/hash.js

@@ -1,6 +1,7 @@
 import * as d3 from 'd3';
 import _ from 'lodash';
-import { utilQsString, utilStringQs } from '../util/index';
+import { modeBrowse } from '../modes';
+import { utilQsString, utilStringQs } from '../util';
 
 
 export function behaviorHash(context) {
@@ -14,8 +15,11 @@ export function behaviorHash(context) {
         if (args.length < 3 || args.some(isNaN)) {
             return true; // replace bogus hash
         } else if (s !== formatter(map).slice(1)) {
-            map.centerZoom([args[2],
-                Math.min(lat, Math.max(-lat, args[1]))], args[0]);
+            var mode = context.mode();
+            if (mode && mode.id.match(/^draw/) !== null) {
+                context.enter(modeBrowse(context));
+            }
+            map.centerZoom([args[2], Math.min(lat, Math.max(-lat, args[1]))], args[0]);
         }
     };