Fix NameError in getquotaroot(), sanctioned by Piers.
diff --git a/Lib/imaplib.py b/Lib/imaplib.py
index 47fbafa..6a27a67 100644
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -441,7 +441,7 @@
 
         (typ, [[QUOTAROOT responses...], [QUOTA responses]]) = <instance>.getquotaroot(mailbox)
         """
-        typ, dat = self._simple_command('GETQUOTA', root)
+        typ, dat = self._simple_command('GETQUOTA', mailbox)
         typ, quota = self._untagged_response(typ, dat, 'QUOTA')
         typ, quotaroot = self._untagged_response(typ, dat, 'QUOTAROOT')
         return typ, [quotaroot, quota]