fix(ngOptions): allow empty option to be removed and re-added

This bug was reported as part of angular/angular.js#15801

src/ng/directive/ngOptions.js

@@ -429,6 +429,9 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
         }
       }
 
+      // The empty option will be compiled and rendered before we first generate the options
+      selectElement.empty();
+
       var providedEmptyOption = !!selectCtrl.emptyOption;
 
       var unknownOption = jqLite(optionTemplate.cloneNode(false));
@@ -545,13 +548,11 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
 
       if (providedEmptyOption) {
 
-        // we need to remove it before calling selectElement.empty() because otherwise IE will
-        // remove the label from the element. wtf?
-        selectCtrl.emptyOption.remove();
-
         // compile the element since there might be bindings in it
         $compile(selectCtrl.emptyOption)(scope);
 
+        selectElement.prepend(selectCtrl.emptyOption);
+
         if (selectCtrl.emptyOption[0].nodeType === NODE_TYPE_COMMENT) {
           // This means the empty option has currently no actual DOM node, probably because
           // it has been modified by a transclusion directive.
@@ -583,8 +584,6 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
 
       }
 
-      selectElement.empty();
-
       // We need to do this here to ensure that the options object is defined
       // when we first hit it in writeNgOptionsValue
       updateOptions();
@@ -649,16 +648,6 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
 
         var groupElementMap = {};
 
-        // Ensure that the empty option is always there if it was explicitly provided
-        if (providedEmptyOption) {
-
-          if (selectCtrl.unknownOption.parent().length) {
-            selectCtrl.unknownOption.after(selectCtrl.emptyOption);
-          } else {
-            selectElement.prepend(selectCtrl.emptyOption);
-          }
-        }
-
         options.items.forEach(function addOption(option) {
           var groupElement;
 

test/ng/directive/ngOptionsSpec.js

@@ -2548,6 +2548,10 @@ describe('ngOptions', function() {
       expect(element.find('option').length).toBe(1);
       option = element.find('option').eq(0);
       expect(option.text()).toBe('A');
+
+      scope.$apply('isBlank = true');
+
+      expect(element).toEqualSelect([''], 'object:4');
     });