maketgz: accept option to include latest commit hash

If the second argument to the script is "commit", then this will
generate a file named `docs/tarball-commit.txt` that contains the latest
commit hash (git rev-parse HEAD) at the time the script runs.

Doing this breaks the reproducibility so it will not be used for "real"
releases but is meant for automated daily snapshots and similar.

Reported-by: Dan Fandrich
Fixes #14363
Closes #14369

maketgz

@@ -32,17 +32,24 @@ export LC_ALL=C
 export TZ=UTC
 
 version="${1:-}"
+cmd="${2:-}"
 
 if [ -z "$version" ]; then
   echo "Specify a version number!"
   exit
 fi
 
-if [ "only" = "${2:-}" ]; then
+echo "$cmd"
+
+only=""
+if [ "only" = "$cmd" ]; then
   echo "Setup version number only!"
   only=1
-else
-  only=
+fi
+
+commit=""
+if [ "commit" = "$cmd" ]; then
+  commit=1
 fi
 
 libversion="$version"
@@ -152,6 +159,11 @@ fi
 echo "produce RELEASE-TOOLS.md"
 ./scripts/release-tools.sh "$timestamp" "$version" > docs/RELEASE-TOOLS.md.dist
 
+if test -n "$commit"; then
+  echo "produce docs/tarball-commit.txt"
+  git rev-parse HEAD >docs/tarball-commit.txt.dist
+fi
+
 ############################################################################
 #
 # Now run make dist to generate a tar.gz archive