When creating a new link or changing an existing link, delete existing ones to the same AGC

src/authentic2_auth_msp/views.py

@@ -462,10 +462,17 @@ class LoginOrLinkView(PopupViewMixin, MspOAuthSessionViewMixin, View):
             self.logger.info('user %r logged in using msp', unicode(user))
             return self.redirect(request)
         elif request.user.is_authenticated():
+            # Old link are deleted
             msp_account, created = models.MspAccount.objects.get_or_create(defaults={
                 'agc': agc,
                 'token': json.dumps(self.token),
                 }, user=request.user)
+            for old_msp_account in models.MspAccount.objects \
+                    .exclude(pk=msp_account.pk) \
+                    .filter(agc=agc):
+                old_msp_account.delete()
+                self.logger.info('msp link deleted for user %r',
+                        unicode(request.user))
             if not created:
                 # Previous links is replaced
                 # XXX: we could add support for multi-link by changing the