Dear Maintainer,
I ran:
sudo sbuild-qemu-create -o /srv/sbuild/qemu/unstable-autopkgtest-amd64.img unstable https://deb.debian.org/debian
It ended with:
Exec: ['sh', '-ec', 'export AUTOPKGTEST_BUILD_QEMU=1; /usr/share/sbuild/sbuild-qemu-create-modscript "$ROOT"']
Exec: ['zerofree', '-v', '/dev/mapper/loop0p1']
ERROR: [Errno 2] No such file or directory: 'zerofree'
ERROR: FileNotFoundError(2, 'No such file or directory')
Exec: ['kpartx', '-dsv', '/srv/sbuild/qemu/unstable-autopkgtest-amd64.img.raw']
Exec: ['losetup', '--json', '-l', '/dev/loop0']
All went fine.
Installing "zerofree" does not show the error.
I expected "zerofree" to be in Depends or Recommends.