Live build debian/stretch/amd64 failed "gpg: signing failed: No secret key"

[cittadinoeuropeo@aol.com]

I periodically build a debian/stretch/amd64 system and all is OK until september 2016.

I have some packages .deb into into directory config/packages.chroot

After september 2016 live build fail. 

Log: 

[2016-11-28 21:44:09] lb chroot_apt install

P: Configuring file /etc/apt/apt.conf

[2016-11-28 21:44:10] lb chroot_archives chroot install

P: Configuring file /etc/apt/sources.list

gpg: WARNING: unsafe permissions on homedir '/root/.gnupg'

gpg: no default secret key: No secret key

gpg: signing failed: No secret key

P: Begin unmounting filesystems...

P: Saving caches...

If config/packages.chroot is empty all is ok.

Thanks for your help.