Comment 6 for bug 451864

I personally did not, but I could have known it. Anjuta and gnome-devel also fail to install on amd64 with the latest Devhelp.
I reckon the changes needed to solve this aren't that big, but it does need to be investigated before the sync request can be honoured.

This most likely has to do with the renaming of libdevhelp-1-0 to libdevhelp-1-1.