          if not self._USE_FORM_OVERLOADING or self._method != 'POST' or not is_form_media_type(self._content_type):
              return
          
          # At this point we're committed to parsing the request as form data.
          self._data = data = self.request.POST
          self._files = self.request.FILES
  
          # Method overloading - change the method and remove the param from the content.
          if self._METHOD_PARAM in data:
              self._method = data[self._METHOD_PARAM].upper()
 
</s> remove             self._content_type = data[self._CONTENTTYPE_PARAM]
            stream = StringIO(data[self._CONTENT_PARAM])
 </s> add             self._content_type = self._data.pop(self._CONTENTTYPE_PARAM)[0]
            stream = StringIO(self._data.pop(self._CONTENT_PARAM)[0]) </s> remove             self._method = data[self._METHOD_PARAM].upper()
 </s> add             # NOTE: unlike `get`, `pop` on a `QueryDict` seems to return a list of values.
            self._method = self._data.pop(self._METHOD_PARAM)[0].upper()
        self._data = data = self.request.POST.copy()
          if not self._USE_FORM_OVERLOADING or self._method != 'POST' or not is_form_media_type(self._content_type):
              return
          
          # At this point we're committed to parsing the request as form data.
        self._data = data = self.request.POST.copy()
          self._files = self.request.FILES
  
          # Method overloading - change the method and remove the param from the content.
          if self._METHOD_PARAM in data:
              self._method = data[self._METHOD_PARAM].upper()
keep keep keep keep replace keep keep keep keep keep
 now cleans data from parameters used for overloads 
djangorestframework/mixins.py