Switch from explicit "stable" / "unstable" to "latest" and "latest-1" based on major.minor releases

This refactor will more closely match how BusyBox does releases -- they always call x.y.0 "unstable" but if it doesn't require any further fixes it never gets a .1 "stable" release (like 1.35 suffered from).  Additionally, they don't seem to really ever have more than two simultaneous release branches (but if they did, we could trivially add a new `latest-2` and be covered):

```console
$ wget -qO- 'https://busybox.net' | grep -ioE '[0-9a-zA-Z ]+ -- BusyBox [0-9.]+ [(](un)?stable[)]' | sed -re 's/(.*) -- (.*)/\2\t\1/' | column -ts$'\t' -R2
BusyBox 1.36.0 (unstable)     3 January 2023
BusyBox 1.35.0 (unstable)   26 December 2021
BusyBox 1.33.2 (stable)     30 November 2021
BusyBox 1.34.1 (stable)    30 September 2021
BusyBox 1.34.0 (unstable)     19 August 2021
BusyBox 1.33.1 (stable)           3 May 2021
BusyBox 1.32.1 (stable)       1 January 2021
BusyBox 1.33.0 (unstable)   29 December 2020
BusyBox 1.32.0 (unstable)       26 June 2020
BusyBox 1.31.1 (stable)      25 October 2019
BusyBox 1.31.0 (unstable)       10 June 2019
BusyBox 1.30.1 (stable)     14 February 2019
BusyBox 1.30.0 (unstable)   31 December 2018
BusyBox 1.29.3 (stable)     9 September 2018
BusyBox 1.29.2 (stable)         31 July 2018
BusyBox 1.29.1 (stable)         15 July 2018
BusyBox 1.29.0 (unstable)        1 July 2018
BusyBox 1.28.4 (stable)          22 May 2018
BusyBox 1.28.3 (stable)         3 April 2018
BusyBox 1.28.2 (stable)        26 March 2018
BusyBox 1.28.1 (stable)     15 February 2018
BusyBox 1.28.0 (unstable)     2 January 2018
BusyBox 1.27.2 (stable)       17 August 2017
BusyBox 1.27.1 (stable)         18 July 2017
BusyBox 1.27.0 (unstable)        3 July 2017
BusyBox 1.26.2 (stable)      10 January 2017
BusyBox 1.26.1 (stable)       2 January 2017
BusyBox 1.26.0 (unstable)   20 December 2016
BusyBox 1.25.1 (stable)       7 October 2016
BusyBox 1.25.0 (unstable)       22 June 2016
BusyBox 1.24.2 (stable)        24 March 2016
BusyBox 1.24.1 (stable)      24 October 2015
BusyBox 1.24.0 (unstable)    12 October 2015
BusyBox 1.23.2 (stable)        23 March 2015
BusyBox 1.23.1 (stable)      27 January 2015
BusyBox 1.23.0 (unstable)   23 December 2014
BusyBox 1.22.1 (stable)      20 January 2014
BusyBox 1.22.0 (unstable)     1 January 2014
BusyBox 1.21.1 (stable)         29 June 2013
BusyBox 1.21.0 (unstable)    21 January 2013
BusyBox 1.20.2 (stable)          2 July 2012
```

Author: tianon

Dockerfile-builder.template

@@ -224,6 +224,7 @@ ENV PATH /usr/src/buildroot/output/host/usr/bin:$PATH
 # sub   1024g/2C766641 2006-12-12
 RUN gpg --batch --keyserver keyserver.ubuntu.com --recv-keys C9E9416F76E610DBD09D040F47B70C55ACC9965B
 
+# https://busybox.net: {{ .date }}
 ENV BUSYBOX_VERSION {{ .version }}
 ENV BUSYBOX_SHA256 {{ .sha256 }}
 

generate-stackbrew-library.sh

@@ -51,8 +51,7 @@ join() {
 	echo "${out#$sep}"
 }
 
-# if stable is 1.32.1 and unstable is 1.33.0, we want busybox:1.33 to point to unstable but busybox:1 (and busybox:latest) to point to stable
-# since stable always comes first, we'll just let it take all the tags it calculates, and use this to remove any overlap when we process unstable :)
+# make sure generic tags like "latest", "1", etc only get used once
 declare -A usedTags=()
 _tags() {
 	local tag first=
@@ -75,20 +74,14 @@ _tags() {
 	return 0
 }
 
-allVersions=()
 for version; do
 	export version
 
 	variants="$(jq -r '.[env.version].variants | map(@sh) | join(" ")' versions.json)"
 	eval "variants=( $variants )"
 
 	fullVersion="$(jq -r '.[env.version].version' versions.json)"
-	allVersions+=( "$fullVersion" )
-	latestVersion="$(xargs -n1 <<<"${allVersions[*]}" | sort -V | tail -1)"
-	if [ "$latestVersion" != "$fullVersion" ]; then
-		# if "unstable" is older than "stable" (1.32.0 unstable vs 1.32.1 stable, for example), skip unstable
-		continue
-	fi
+	stability="$(jq -r '.[env.version].stability' versions.json)"
 
 	versionAliases=()
 	while [ "${fullVersion%.*}" != "$fullVersion" ]; do
@@ -97,7 +90,7 @@ for version; do
 	done
 	versionAliases+=(
 		$fullVersion
-		$version # "stable", "unstable"
+		$stability # "stable", "unstable"
 		latest
 	)