Fixed #17867 -- Made email validation pass with IDN domains

Thanks Pierre Matri for the report and the initial patch.

django/core/validators.py

@@ -99,7 +99,7 @@ email_re = re.compile(
     r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*"  # dot-atom
     # quoted-string, see also http://tools.ietf.org/html/rfc2822#section-3.2.5
     r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-\011\013\014\016-\177])*"'
-    r')@((?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?$)'  # domain
+    r')@((?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)$)'  # domain
     r'|\[(25[0-5]|2[0-4]\d|[0-1]?\d?\d)(\.(25[0-5]|2[0-4]\d|[0-1]?\d?\d)){3}\]$', re.IGNORECASE)  # literal form, ipv4 address (SMTP 4.1.3)
 validate_email = EmailValidator(email_re, _('Enter a valid email address.'), 'invalid')
 

tests/modeltests/validators/tests.py

@@ -28,6 +28,7 @@ TEST_DATA = (
     (validate_email, 'email@[127.0.0.1]', None),
     (validate_email, 'example@valid-----hyphens.com', None),
     (validate_email, 'example@valid-with-hyphens.com', None),
+    (validate_email, 'test@domain.with.idn.tld.उदाहरण.परीक्षा', None),
 
     (validate_email, None, ValidationError),
     (validate_email, '', ValidationError),