diff --git a/airflow/configuration.py b/airflow/configuration.py
index <HASH>..<HASH> 100644
--- a/airflow/configuration.py
+++ b/airflow/configuration.py
@@ -302,7 +302,7 @@ class ConfigParserWithDefaults(ConfigParser):
         self.defaults = defaults
         ConfigParser.__init__(self, *args, **kwargs)
 
-    def get(self, section, key):
+    def get(self, section, key, **kwargs):
         section = str(section).lower()
         key = str(key).lower()
         d = self.defaults
@@ -315,7 +315,7 @@ class ConfigParserWithDefaults(ConfigParser):
 
         # ...then the config file
         elif self.has_option(section, key):
-            return expand_env_var(ConfigParser.get(self, section, key))
+            return expand_env_var(ConfigParser.get(self, section, key, **kwargs))
 
         # ...then the defaults
         elif section in d and key in d[section]:
Py<I>: Pass ConfigParser's extra kwargs through

In Python <I> ConfigParser has it's own string interpolation which recursively
calls get, but with extra kwargs, raw and fallback.

Accept these and pass them straight on to ConfigParser