It was fixed in db1ecc8212defdd183abbb6b1407fcc8d2dc9552 for 2.1.
In 2.1, HDRLEN=0 for all callers, so, there will be no same "Ohhhh jeeee" any more.
In 1.4 and 2.0, HDRLEN is used as a hint. There is no need to change 1.4 and
2.0. Detail is described in:
https://lists.gnupg.org/pipermail/gnupg-devel/2016-June/031178.html