Comment # 4 on bug 907545 from Reinhard Max

Submitted to Factory and as a maintenance update to 13.2 and 42.1.

Also, the curl team has picked up my suggestions, resulting in these three
commits:

https://github.com/curl/curl/commit/9adf3c473a01b289
https://github.com/curl/curl/commit/434f8d0389f2969b
https://github.com/curl/curl/commit/80388edefca58f81