I tried the command has you suggested:

httrack <https://dist.apache.org/repos/dist/dev/commons/dbcp> -O /tmp/dist
+https://dist.apache.org/repos/dist/dev/commons/dbcp/*

However, it has exactly the same behaviour as the -D flag. It goes up and
downloads the siblings folders if the first url does not end with a /, and it
does not goes up if the URL ends with a /.