After analysis, it appears that libept does not generate anymore
binary libept1 but libept1.4.12|
However I didn't find where comes from the libept1 dependency with debootstrap.
libept1 cannot be used anymore as it does not match the libapt-pkg version.
-- gpg key id: 4096R/326D8438 (keyring.debian.org) Key fingerprint = 5FB4 6F83 D3B9 5204 6335 D26D 78DC 68DB 326D 8438