Ok, ACKed and patch made. I also found what the culprit was (and why it worked on my system). The patch is really similar to Cyrille's, but more general.
I'm marking it for 1.7.3 -- it would deserve a 220.127.116.11, but I'm quite fed up of doing minor 1.7.2 releases. So please wait a couple of days, so that I can fix more bugs for 1.7.3.