          if not auth or auth[0].lower() != b'basic':
              return None
  
          if len(auth) == 1:
              msg = 'Invalid basic header. No credentials provided.'
              raise exceptions.AuthenticationFailed(msg)
          elif len(auth) > 2:
              msg = 'Invalid basic header. Credentials string should not contain spaces.'
              raise exceptions.AuthenticationFailed(msg)
  
 
</s> remove             msg = 'Invalid token header. No credentials provided.'
 </s> add             msg = _("Invalid token header. No credentials provided.") </s> remove             msg = 'Invalid basic header. Credentials string should not contain spaces.'
 </s> add             msg = _("Invalid basic header. Credentials string should not contain spaces.") </s> remove             msg = 'Invalid token header. Token string should not contain spaces.'
 </s> add             msg = _("Invalid token header. Token string should not contain spaces.") </s> remove             msg = 'Invalid basic header. Credentials not correctly base64 encoded'
 </s> add             msg = _("Invalid basic header. Credentials not correctly base64 encoded.") </s> remove                     msg = _('User account is disabled.')
 </s> add                     msg = _("User account is disabled.")
            msg = _("Invalid basic header. No credentials provided.")
          if not auth or auth[0].lower() != b'basic':
              return None
  
          if len(auth) == 1:
            msg = _("Invalid basic header. No credentials provided.")
              raise exceptions.AuthenticationFailed(msg)
          elif len(auth) > 2:
              msg = 'Invalid basic header. Credentials string should not contain spaces.'
              raise exceptions.AuthenticationFailed(msg)
  
keep keep keep keep replace keep keep keep keep keep
 use double quotes for user visible strings; end user visible strings in full stops; add some missing translation tags 
rest_framework/authentication.py