fix 19420, make sure we override cached redirector type if it changes r/sr=sspitzer

mailnews/imap/src/nsImapIncomingServer.cpp

@@ -1409,6 +1409,7 @@ NS_IMETHODIMP nsImapIncomingServer::GetRedirectorType(char **redirectorType)
 
 NS_IMETHODIMP nsImapIncomingServer::SetRedirectorType(const char *redirectorType)
 {
+  m_redirectorType = redirectorType;
   return (SetCharValue("redirector_type", redirectorType));
 }