samba-common, noarch package. samba-common-bin depends on it. If samba-common is 2.15 and security, it overwrites 2.14 amd64 package, thus remoing samba-common-bin, which hasn't received the amd64 2.15 update yet, it depends on 2.14 samba-common, and thus the samba-common 2.15 upgrade in practice removes samba-common-bin due to unsatisfiable dependencies.
Create an MCE and report to Debian/Canonical if possible.
Example:
samba-common, noarch package. samba-common-bin depends on it. If samba-common is 2.15 and security, it overwrites 2.14 amd64 package, thus remoing samba-common-bin, which hasn't received the amd64 2.15 update yet, it depends on 2.14 samba-common, and thus the samba-common 2.15 upgrade in practice removes samba-common-bin due to unsatisfiable dependencies.
Create an MCE and report to Debian/Canonical if possible.