don't allow to continue registering an account if we only get instructions. Fixes #6957

src/config.py

@@ -3522,6 +3522,7 @@ class AccountCreationWizardWindow:
 
     def on_back_button_clicked(self, widget):
         cur_page = self.notebook.get_current_page()
+        self.forward_button.set_sensitive(True)
         if cur_page in (1, 2):
             self.notebook.set_current_page(0)
             self.back_button.set_sensitive(False)
@@ -3763,6 +3764,18 @@ class AccountCreationWizardWindow:
             self.data_form_widget = dataforms_widget.DataFormWidget(dataform)
         else:
             self.data_form_widget = FakeDataForm(obj.config)
+        empty_config = True
+        for field in obj.config:
+            if field == 'instructions':
+                continue
+            if not obj.config[field]:
+                # ignore empty tag
+                continue
+            empty_config = False
+            break
+        if not obj.is_form and empty_config:
+            self.forward_button.set_sensitive(False)
+            self.notebook.set_current_page(4) # show form page
         self.data_form_widget.show_all()
         self.xml.get_object('form_vbox').pack_start(self.data_form_widget)
         self.ssl_fingerprint = obj.ssl_fingerprint