Since GPG 2 was set as default for Debian (Sid, August 2016), an error message appeared inside jails triggered by chroot, when using debuild/debsign commands:

clearsign failed: Inappropriate ioctl for device

The problem is that GPG 2 uses a dialog window to ask for a passphrase. This dialog window needs a tty (from /dev/pts/ directory). To solve the problem, you can use the following command (inside the jail):

# mount devpts -t devpts /dev/pts

Alternatively, you can add to /etc/fstab file in jail:

devpts /dev/pts devpts defaults 0 0

and use the command:

# mount /dev/pts

Enjoy!