  
      pdict = {}
      maxcnts = {}
      catalog = {}
      for k, v in t.items():
          if k == '':
              continue
          if isinstance(k, six.string_types):
              catalog[k] = v
          elif isinstance(k, tuple):
              msgid = k[0]
 
</s> remove         if isinstance(k, six.string_types):
            catalog[k] = v
        elif isinstance(k, tuple):
            msgid = k[0]
            cnt = k[1]
 </s> add         if isinstance(key, six.string_types):
            catalog[key] = value
        elif isinstance(key, tuple):
            msgid = key[0]
            cnt = key[1] </s> remove             pdict.setdefault(msgid, {})[cnt] = v
 </s> add             pdict.setdefault(msgid, {})[cnt] = value </s> remove             raise TypeError(k)
 </s> add             raise TypeError(key) </s> remove     # add the filesystem paths listed in the LOCALE_PATHS setting
    paths.extend(reversed(settings.LOCALE_PATHS))
    # first load all english languages files for defaults
    for path in paths:
        try:
            catalog = gettext_module.translation(domain, path, ['en'])
            t.update(catalog._catalog)
        except IOError:
            pass
        else:
            # 'en' is the selected language and at least one of the packages
            # listed in `packages` has an 'en' catalog
            if en_selected:
                en_catalog_missing = False
    # next load the settings.LANGUAGE_CODE translations if it isn't english
    if default_locale != 'en':
        for path in paths:
            try:
                catalog = gettext_module.translation(domain, path, [default_locale])
            except IOError:
                catalog = None
            if catalog is not None:
                t.update(catalog._catalog)
    # last load the currently selected language, if it isn't identical to the default.
    if locale != default_locale:
        # If the currently selected language is English but it doesn't have a
        # translation catalog (presumably due to being the language translated
        # from) then a wrong language catalog might have been loaded in the
        # previous step. It needs to be discarded.
        if en_selected and en_catalog_missing:
            t = {}
        else:
            locale_t = {}
            for path in paths:
                try:
                    catalog = gettext_module.translation(domain, path, [locale])
                except IOError:
                    catalog = None
                if catalog is not None:
                    locale_t.update(catalog._catalog)
            if locale_t:
                t = locale_t
 </s> add     trans = DjangoTranslation(locale, domain=domain, localedirs=paths)
    trans_cat = trans._catalog
 </s> remove     t = {}
 </s> add 
    trans_fallback_cat = trans._fallback._catalog if trans._fallback else {}
    for key, value in itertools.chain(six.iteritems(trans_cat), six.iteritems(trans_fallback_cat)):
        if key == '' or key in catalog:
  
      pdict = {}
      maxcnts = {}
      catalog = {}
    trans_fallback_cat = trans._fallback._catalog if trans._fallback else {}
    for key, value in itertools.chain(six.iteritems(trans_cat), six.iteritems(trans_fallback_cat)):
        if key == '' or key in catalog:
    trans_fallback_cat = trans._fallback._catalog if trans._fallback else {}
    for key, value in itertools.chain(six.iteritems(trans_cat), six.iteritems(trans_fallback_cat)):
        if key == '' or key in catalog:
              continue
          if isinstance(k, six.string_types):
              catalog[k] = v
          elif isinstance(k, tuple):
              msgid = k[0]
keep keep keep keep replace replace keep keep keep keep keep
 Reused the DjangoTranslation class for the javascript_catalog view

Thanks Tim Graham and Cristiano Coelho for the reviews.
Refs #26328, #26319. 
django/views/i18n.py