Enhance "generate-stackbrew-library.sh" to only take into account changes to the Dockerfile or files from COPY in the Dockerfile for choosing the commit hash for a particular directory

Author: tianon

generate-stackbrew-library.sh

@@ -15,7 +15,7 @@ url='git://github.com/docker-library/postgres'
 echo '# maintainer: InfoSiftr <github@infosiftr.com> (@infosiftr)'
 
 for version in "${versions[@]}"; do
-	commit="$(git log -1 --format='format:%H' -- "$version")"
+	commit="$(cd "$version" && git log -1 --format='format:%H' -- Dockerfile $(awk 'toupper($1) == "COPY" { for (i = 2; i < NF; i++) { print $i } }' Dockerfile))"
 	fullVersion="$(grep -m1 'ENV PG_VERSION ' "$version/Dockerfile" | cut -d' ' -f3 | cut -d- -f1 | sed 's/~/-/g')"
 	versionAliases=( $fullVersion $version ${aliases[$version]} )