A change to how calm expires packages

[Jon Turney <jon.turney@dronecode.org.uk>]

To try to avoid packages lingering in the 'test' status indefinitely 
(which leads to them not being installed by most users, as they don't 
run setup with 'consider test packages' enabled, thus these packages 
generally aren't getting used, so having them isn't generating much 
value), I'm planning to change how calm expires packages:

Currently (in the absence of configuration otherwise [1]), calm will 
retain up to 3 non-test versions, and 3 test versions, and expire all 
other versions.

I plan to change this to also expire test versions which are superseded 
by a non-test version (that is: expire test versions where a non-test 
version with a higher version number exists).

I believe this makes the default behaviour closer to what package 
maintainers are likely to want to happen.

This change will cause the following packages to be removed:

_autorebase-001091-0.1
cygutils-1.4.16-4
cygwin-3.3.0-0.1.9814cfd8f693
cygwin-3.3.0-0.2.6c1f49f83fde
fontforge-20201107p2-1
fontforge-20201107p8-1
gcc-11.2.0-0
grep-3.6-1
grep-3.7-1
gzip-1.10-1
libftdi1-1.4-1
libiconv-1.16-1
meson-0.54.2-3
mingw64-i686-gcc-11.1.0-0.1
mingw64-i686-gcc-11.2.0-0
mingw64-i686-gcc-7.3.0-1
mingw64-x86_64-gcc-11.1.0-0.1
mingw64-x86_64-gcc-11.2.0-0.1
mingw64-x86_64-gcc-7.3.0-1
openbabel-3.1.1p36-1
openbabel-3.1.1p36-2
rdiff-backup-2.0.0-1
readline-8.1-1
screen-4.6.2-3
texlive-collection-latexrecommended-doc-20210118-2
xorg-server-21.1.0-1


Brian, Ken,

The only packages I can see where this seems like it will do the wrong 
thing are listed below.  Before deploying this, would you like me to:?

grep: untest 3.6-1 and expire 3.0.1
gzip: untest 1.10-1 and expire 1.7-2
texlive-collection-latexrecommended-doc: untest 20210118-2 and expire 
20210118-1

[1] See https://cygwin.com/packaging-hint-files.html#override.hint.  Not 
that override.hint files do not apply recursively currently.