scripts/make-archive.sh: more precise tag detection

This works better in the current case when master branch with the most
recent 5.7.0 tag got merged into the 6.0 branch.  In that case we do not
want the most recent *generally* reachable tag, and git-describe has
probably good logic for this (using first-parent jumps I guess).

scripts/make-archive.sh

@@ -11,7 +11,7 @@ cd "$(dirname ${0})/.."
 
 if ! git describe --tags --exact-match; then
     # devel version
-    VERSION_TAG=$(git tag --merged HEAD --sort=-taggerdate | head -1)
+    VERSION_TAG=$(git describe --tags | cut -d- -f1)
     VERSION=${VERSION_TAG#v}
     GIT_HASH=$(git rev-parse --short=6 HEAD)
     N_COMMITS=$(git rev-list $VERSION_TAG.. --count)