Remove check for field length; the check is already done, so the code…

… isn't called.

git-svn-id: https://svn.calendarserver.org/repository/calendarserver/CalendarServer/trunk@11923 e27351fd-9f3e-4f54-a53b-843176b1656c

twext/who/directory.py

@@ -291,11 +291,6 @@ def __init__(self, service, fields):
 
             if FieldName.isMultiValue(fieldName):
                 values = fields[fieldName]
-                if len(values) == 0:
-                    raise ValueError(
-                        "{0} field must have at least one value."
-                        .format(fieldName)
-                    )
                 for value in values:
                     if not value:
                         raise ValueError(