As shown below, aptitude has been progressively downgraded from “important” in oldstable (Wheezy) to “standard” in stable (Jessie), “standard” in testing (Stretch) and finally to “optional” in unstable (Sid)
rbthomas@cube:~$ aptitude -vv show aptitude | egrep '^(Priority|Version|Archive): ' | sed 's/^Version: / &/' Version: 0.7.4-1 Priority: optional Archive: unstable Version: 0.7.4-1 Priority: optional Archive: unstable Version: 0.7.4-1 Priority: optional Archive: now Version: 0.7.2-1 Priority: optional Archive: testing Version: 0.6.11-1+b1 Priority: standard Archive: stable Version: 0.6.11-1+b1 Priority: standard Archive: stable Version: 0.6.8.2-1 Priority: important Archive: oldstable And exim4 has gone from “standard” in all versions (at least those I have access to) before testing to “optional” in testing and above. rbthomas@cube:~$ aptitude -vv show exim4 | egrep '^(Priority|Version|Archive): ' | sed 's/^Version: / &/' Version: 4.86-4 Priority: optional Archive: unstable Version: 4.86-4 Priority: optional Archive: testing Version: 4.86-4 Priority: optional Archive: unstable Version: 4.86-4 Priority: optional Archive: now Version: 4.84-8 Priority: standard Archive: stable Version: 4.84-8 Priority: standard Archive: stable Version: 4.80-7+deb7u1 Priority: standard Archive: oldstable This (and several other downgrades) seem to have been discussed on the debian-boot list in May, 2015. See the thread that starts at https://lists.debian.org/debian-boot/2015/05/msg00156.html for details. I have a small script I run after finishing any install that loads and configures several packages that I use regularly but are not included in a standard install. It just got a whole lot bigger! Sigh! Rick