py3: Replace basestring with six.string_types

Patch generated by the command:

  sixer.py basestring horizon/ openstack_dashboard/ tools/

Partial-Implements: blueprint porting-python3
Change-Id: I6fd251243a058457f69907eb1111f559a224e1cb

horizon/forms/fields.py

@@ -15,6 +15,7 @@
 import re
 
 import netaddr
+import six
 
 from django.core.exceptions import ValidationError  # noqa
 from django.core import urlresolvers
@@ -189,7 +190,7 @@ class SelectWidget(widgets.Select):
             html_attrs = self.transform_html_attrs(option_label)
             other_html += flatatt(html_attrs)
 
-        if not isinstance(option_label, (basestring, Promise)):
+        if not isinstance(option_label, (six.string_types, Promise)):
             for data_attr in self.data_attrs:
                 data_value = html.conditional_escape(
                     force_text(getattr(option_label,

horizon/tables/actions.py

@@ -753,7 +753,7 @@ class BatchAction(Action):
         action_attr = getattr(self, "action_%s" % action_type)
         if self.use_action_method:
             action_attr = action_attr(count)
-        if isinstance(action_attr, (basestring, Promise)):
+        if isinstance(action_attr, (six.string_types, Promise)):
             action = action_attr
         else:
             toggle_selection = getattr(self, "current_%s_action" % action_type)

horizon/workflows/base.py

@@ -318,7 +318,7 @@ class Step(object):
                     # If it's callable we know the function exists and is valid
                     self._handlers[key].append(possible_handler)
                     continue
-                elif not isinstance(possible_handler, basestring):
+                elif not isinstance(possible_handler, six.string_types):
                     raise TypeError("Connection handlers must be either "
                                     "callables or strings.")
                 bits = possible_handler.split(".")

openstack_dashboard/dashboards/project/stacks/mappings.py

@@ -136,7 +136,7 @@ def resource_to_url(resource):
 def stack_output(output):
     if not output:
         return u''
-    if isinstance(output, basestring):
+    if isinstance(output, six.string_types):
         parts = urlparse.urlsplit(output)
         if parts.netloc and parts.scheme in ('http', 'https'):
             url = html.escape(output)