fix(searchBox): do not trigger a search when input value is the same

This also avoids another IE11/10 bug where input event is triggered as
soon as the user clicks in an input having a placeholder property.

src/widgets/search-box/__tests__/search-box-test.js

@@ -209,12 +209,18 @@ describe('searchBox()', () => {
       container = document.body.appendChild(document.createElement('input'));
     });
 
-    function simulateInputEvent(query) {
+    function simulateInputEvent(query, stateQuery) {
       if (query === undefined) {
         query = 'test';
       }
+
       // Given
-      helper.state.query = 'tes';
+      if (stateQuery !== undefined) {
+        helper.state.query = stateQuery;
+      } else {
+        helper.state.query = 'tes';
+      }
+
       // When
       widget.init({state, helper, onHistoryChange});
       // Then
@@ -237,6 +243,12 @@ describe('searchBox()', () => {
         simulateInputEvent();
         expect(helper.setQuery.calledOnce).toBe(true);
       });
+
+      it('does nothing when query is the same as state', () => {
+        simulateInputEvent('test', 'test');
+        expect(helper.setQuery.calledOnce).toBe(false);
+        expect(helper.search.called).toBe(false);
+      });
     });
 
     context('non-instant search', () => {

src/widgets/search-box/search-box.js

@@ -155,6 +155,10 @@ function searchBox({
       }
 
       function maybeSearch(query) {
+        if (query === helper.state.query) {
+          return;
+        }
+
         if (queryHook) {
           queryHook(query, search);
           return;