b=180806 IMAP backend should avoid unnecessary logout

r=bienvenu sr=sspitzer

mailnews/imap/src/nsImapProtocol.cpp

@@ -1000,6 +1000,8 @@ nsImapProtocol::TellThreadToDie(PRBool isSaveToClose)
   nsresult rv = NS_OK;
   PRUint32 writeCount;
 
+  if (m_currentServerCommandTagNumber > 0)
+  {
     if (closeNeeded && GetDeleteIsMoveToTrash() &&
         TestFlag(IMAP_CONNECTION_IS_OPEN) && m_outputStream)
     {
@@ -1020,6 +1022,7 @@ nsImapProtocol::TellThreadToDie(PRBool isSaveToClose)
                                  &writeCount);
       Log("SendData", "TellThreadToDie", command.get());
     }
+  }
 
   if (mAsyncReadRequest)
     mAsyncReadRequest->Cancel(NS_OK);