supplimental fix for bug #244217

thanks to burpmaster@truffula.net for catching a bad regression.

r/sr=bienvenu

mailnews/base/util/nsMsgDBFolder.cpp

@@ -1089,7 +1089,9 @@ nsresult nsMsgDBFolder::GetFolderCacheKey(nsIFileSpec **aFileSpec)
 
 			// create the .msf file
 			// see bug #244217 for details
-			dbPath->Touch();
+			PRBool exists;
+			if (NS_SUCCEEDED(dbPath->Exists(&exists)) && !exists)
+				dbPath->Touch();
 		}
 	}
 	return rv;