Merge branch 'hotfix/4599' into develop

Forward port zendframework/zendframework#4599

Conflicts:
	tests/ZendTest/InputFilter/InputTest.php

src/Input.php

@@ -298,6 +298,7 @@ public function merge(InputInterface $input)
     {
         $this->setAllowEmpty($input->allowEmpty());
         $this->setBreakOnFailure($input->breakOnFailure());
+        $this->setContinueIfEmpty($input->continueIfEmpty());
         $this->setErrorMessage($input->getErrorMessage());
         $this->setName($input->getName());
         $this->setRequired($input->isRequired());

test/InputTest.php

@@ -302,4 +302,14 @@ public function testFallbackValue($fallbackValue)
         $this->assertEmpty($this->input->getMessages());
         $this->assertSame($fallbackValue, $this->input->getValue());
     }
+
+    public function testMergeRetainsContinueIfEmptyFlag()
+    {
+        $input = new Input('foo');
+        $input->setContinueIfEmpty(true);
+
+        $input2 = new Input('bar');
+        $input2->merge($input);
+        $this->assertTrue($input2->continueIfEmpty());
+    }
 }