DOBISSUE date format changed after customer tries to register with same email address.

Author: KaushikChavda

app/code/Magento/Customer/Block/Widget/Dob.php

@@ -128,6 +128,7 @@ protected function applyOutputFilter($value)
     {
         $filter = $this->getFormFilter();
         if ($filter) {
+            $value = date('Y-m-d',strtotime($value));
             $value = $filter->outputFilter($value);
         }
         return $value;

lib/internal/Magento/Framework/Data/Form/Filter/Date.php

@@ -75,7 +75,7 @@ public function inputFilter($value)
     public function outputFilter($value)
     {
         $filterInput = new \Zend_Filter_LocalizedToNormalized(
-            ['date_format' => $this->_dateFormat, 'locale' => $this->localeResolver->getLocale()]
+            ['date_format' => DateTime::DATE_INTERNAL_FORMAT, 'locale' => $this->localeResolver->getLocale()]
         );
         $filterInternal = new \Zend_Filter_NormalizedToLocalized(
             ['date_format' => $this->_dateFormat, 'locale' => $this->localeResolver->getLocale()]
@@ -85,4 +85,4 @@ public function outputFilter($value)
         $value = $filterInternal->filter($value);
         return $value;
     }
-}
+}