make as_producer handle formdef_reference values

combo_plugin_gnm/templatetags/gnm.py

@@ -128,6 +128,8 @@ def is_place_page(page):
 
 @register.filter
 def as_producer(slug):
+    if ':' in slug: # formdef_reference
+        slug = slug.split(':')[0]
     if slug.startswith('_'):
         collectivity = slug.split('_')[1]
         return {'slug': collectivity,