Package: ftp.debian.org Severity: important
"python-notebook_4.2.3-4+deb9u1_all.deb: Built-Using refers to non-existing source package backbone (= 1.3.3~dfsg-1)" I tried to upload jupyter-notebook to stretch-security as part of LTS. But package rejected to due to above reason. Please move required source packages onto security-master for accepting jupyter-notebook. I've forwarded the rejected mail to ftpmaster@d.o and pinged on IRC as well. Apologies if this is redundant. --abhijith