fix "gramps --databases"

gramps/cli/argparser.py

@@ -326,7 +326,7 @@ class ArgParser:
                     print()
                 sys.exit(0)
             elif option in ['-b', '--databases']:
-                default = config.data["behavior"]["database-backend"]
+                default = config.data["database"]["backend"]
                 pmgr = BasePluginManager.get_instance()
                 pmgr.reg_plugins(PLUGINS_DIR, self, None)
                 pmgr.reg_plugins(USER_PLUGINS, self, None, load_on_reg=True)

gramps/plugins/db/dummydb.py

@@ -210,6 +210,16 @@ class DummyDb(M_A_M_B("NewBaseClass", (DbReadBase, Callback, object,), {})):
 
     __signals__ = {}
 
+    @classmethod
+    def get_class_summary(cls):
+        """
+        Return a diction of information about this database.
+        """
+        summary = {
+            "Database type": cls.__name__,
+        }
+        return summary
+
     def __init__(self):
         """
         Create a new DummyDb instance.