fix for #16341

from putterman, who gave me the fix:

"Whenever you add something to RDF through an observer notification, RDF
verifies that you really have it by calling HasAssertion.  Our implementation of HasAssertion for adding a folder to a folder consists of seeing if the the
child folder's parent is equal to the parent passed in.  Because we weren't setting the parent, the child's parent was null which wasn't equal to the parent
passed in and the whole operation failed.  This prevents that from happening."


git-svn-id: svn://10.0.0.236/trunk@53248 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/mailnews/news/src/nsNewsFolder.cpp

@@ -230,6 +230,7 @@ nsMsgNewsFolder::AddSubfolder(nsAutoString name, nsIMsgFolder **child, char *set
 	if(folderSupports)
 		mSubFolders->AppendElement(folderSupports);
 	*child = folder;
+	folder->SetParent(this);
 	NS_ADDREF(*child);
 
 	return rv;