Hi,
I am not a Gnome user, but somehow had this package installed on machine A. I was logged in on machine A, but had a screen lock on. On machine B, I was also logged in, running something like "ssh -XCA machineA" where I tried to "gbp buildpackage". This got stuck at the signing phase, with no output on my terminal (ie, in the SSH session). If I typed something, I had local echo. I could kill the program by typing Ctrl-C. Both machines are running the latest Stretch/amd64. Thanks, Toni