Ah! stretch! that's why you weren't seeing the same FTBFS I was working on (which is caused by the new gnupg, and thus right now only in sid).
I've investigated a bit on the issue, and found that gnupg is indeed installed when installing build-essential, but only as a Recommends, and thus it won't be installed on the autobuilders. This made me learn that I should really recreate my (p|cow)builder images now and then: I still had gnupg installed by default in the base image for historical reasons and it hadn't been autoremoved because of that Recommends. Anyway, the pending upload that I've prepared for the other FTBFS had to add an explicit dependency on gnupg1, which should fix also this issue; I won't remove it when I'll be able to go back on depending on gnupg. Thanks again for your report. -- Elena ``of Valhalla''