Providing default value to get() to prevent a runtime error (#469)

auslib/blobs/apprelease.py

@@ -967,7 +967,7 @@ def _getUpdateLineXML(self, updateQuery, update_type):
             # Rules table to avoid confusion.
             "type": update_type,
         }
-        for group in self.get("updateLine"):
+        for group in self.get("updateLine", []):
             condition_results = []
             for condition, values in group["for"].items():
                 matches = False