fix view commands like label leaving local mail db invalid, causing mail msgs to get doubled up, 227490 r/a=sspitzer, sr=mscott

mailnews/db/msgdb/src/nsMailDatabase.cpp

@@ -248,6 +248,7 @@ NS_IMETHODIMP nsMailDatabase::EndBatch()
     m_folderStream = nsnull;
     m_ownFolderStream = PR_FALSE;
   }
+  SetFolderInfoValid(m_folderSpec, 0, 0);
   return NS_OK;
 }