Fix mapper configuration.

debexpo/model/plugin_results.py

@@ -64,10 +64,10 @@ class PluginResultData(OrmObject):
 plugin_result_mapper = orm.mapper(PluginResult,
     t_plugin_results,
     polymorphic_on = t_plugin_results.c.plugin,
-    polymorphic_identity = 'plugin_results', \
-        properties = {
-            'plugin_result' : orm.relation(PackageVersion,
-                                           backref='plugin_results'),
+    polymorphic_identity = 'plugin_results',
+    properties = {
+        'package_version' : orm.relation(PackageVersion,
+                                         backref='plugin_results'),
         }
     )