Run pformat before adding to seen_layers
Run pformat before adding to seen_layers

Fixes problems where repr may render more templates

jazzband/django-debug-toolbar,tim-schilling/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,spookylukey/django-debug-toolbar,tim-schilling/django-debug-toolbar,jazzband/django-debug-toolbar,jazzband/django-debug-toolbar,tim-schilling/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar,spookylukey/django-debug-toolbar,spookylukey/django-debug-toolbar,django-debug-toolbar/django-debug-toolbar