[damned-lies] Fixes #92 (again) - Redirect after popup login form

[Claude Paroz <claudep src gnome org>]

commit a233dabdb3e97c79173ca8ebcda43cb5172ced2d
Author: Claude Paroz <claude 2xlibre net>
Date:   Sat Aug 18 16:43:57 2018 +0200

    Fixes #92 (again) - Redirect after popup login form

 common/views.py | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/common/views.py b/common/views.py
index 00f2262d..84236356 100644
--- a/common/views.py
+++ b/common/views.py
@@ -52,6 +52,12 @@ class LoginView(AuthLoginView):
             context['referer'] = self.request.META.get('HTTP_REFERER', '')
         return context
 
+    def get_redirect_url(self):
+        url = super().get_redirect_url()
+        if not url:
+            url = self.request.META.get('HTTP_REFERER', '')
+        return url
+
     def form_valid(self, form):
         response = super().form_valid(form)
         if Role.objects.filter(person__username=self.request.user.username).count() < 1: