fix 3906 moved target cancellation up so (#3909)

* moved target cancellation up
* added tests

src/canvas.class.js

@@ -1101,6 +1101,7 @@
       // first check current group (if one exists)
       // active group does not check sub targets like normal groups.
       // if active group just exits.
+      this.targets = [];
       if (activeGroup && !skipGroup && activeGroup === this._searchPossibleTargets([activeGroup], pointer)) {
         this._fireOverOutEvents(activeGroup, e);
         return activeGroup;
@@ -1120,7 +1121,6 @@
         }
       }
 
-      this.targets = [];
       var target = this._searchPossibleTargets(this._objects, pointer);
       if (e[this.altSelectionKey] && target && activeTarget && target !== activeTarget) {
         target = activeTarget;

test/unit/canvas.js

@@ -435,6 +435,37 @@
     canvas.remove(group);
   });
 
+  test('findTarget with subTargetCheck on activeObject', function() {
+    var rect = makeRect({ left: 0, top: 0 }),
+        rect2 = makeRect({ left: 30, top:  30}), target,
+        group = new fabric.Group([rect, rect2]);
+
+    canvas.add(group);
+    canvas.setActiveObject(group);
+    group.subTargetCheck = true;
+    target = canvas.findTarget({
+      clientX: 9, clientY: 9
+    });
+    equal(target, group, 'Should return the group');
+    equal(canvas.targets[0], rect, 'should return the rect');
+
+    target = canvas.findTarget({
+      clientX: 9, clientY: 9
+    });
+
+    target = canvas.findTarget({
+      clientX: 9, clientY: 9
+    });
+
+    target = canvas.findTarget({
+      clientX: 9, clientY: 9
+    });
+
+    equal(canvas.targets.length, 1, 'multiple calls to subtarget should not add more to targets');
+
+    canvas.remove(group);
+  });
+
   test('findTarget with perPixelTargetFind', function() {
     ok(typeof canvas.findTarget == 'function');
     var triangle = makeTriangle({ left: 0, top: 0 }), target;