fix(VTextField): on emit change when initial value != lazy

fixes #5070

Author: johnleider

Diff for: packages/vuetify/src/components/VTextField/VTextField.ts

@@ -474,7 +474,13 @@ export default baseMixins.extend<options>().extend({
       this.badInput = target.validity && target.validity.badInput
     },
     onKeyDown (e: KeyboardEvent) {
-      if (e.keyCode === keyCodes.enter) this.$emit('change', this.internalValue)
+      if (
+        e.keyCode === keyCodes.enter &&
+        this.lazyValue !== this.initialValue
+      ) {
+        this.initialValue = this.lazyValue
+        this.$emit('change', this.initialValue)
+      }
 
       this.$emit('keydown', e)
     },

Diff for: packages/vuetify/src/components/VTextField/__tests__/VTextField.spec.ts

@@ -628,19 +628,26 @@ describe('VTextField.ts', () => { // eslint-disable-line max-statements
     expect(input.element.id).toBe('foo')
   })
 
-  it('should fire change event when pressing enter', () => {
+  it('should fire change event when pressing enter and value has changed', () => {
     const wrapper = mountFunction()
     const input = wrapper.find('input')
     const change = jest.fn()
+    const el = input.element as HTMLInputElement
 
     wrapper.vm.$on('change', change)
 
     input.trigger('focus')
-    input.element.value = 'foo'
+    el.value = 'foo'
     input.trigger('input')
     input.trigger('keydown.enter')
     input.trigger('keydown.enter')
 
+    expect(change).toHaveBeenCalledTimes(1)
+
+    el.value = 'foobar'
+    input.trigger('input')
+    input.trigger('keydown.enter')
+
     expect(change).toHaveBeenCalledTimes(2)
   })