build: add script to delete old change log files

scripts/rel/delete-old-changelog.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+[ "${DEBUG:-0}" = 1 ] && set -x
+
+top_dir="$(git rev-parse --show-toplevel)"
+prev_ce_tag="$("$top_dir"/scripts/find-prev-rel-tag.sh 'emqx')"
+prev_ee_tag="$("$top_dir"/scripts/find-prev-rel-tag.sh 'emqx-enterprise')"
+
+## check if a file is included in the previous release
+is_released() {
+    file="$1"
+    prev_tag="$2"
+    # check if file exists in the previous release
+    if git show "$prev_tag:$file" >/dev/null 2>&1; then
+        return 1
+    else
+        return 0
+    fi
+}
+
+## loop over files in $top_dir/changes/ce
+## and delete the ones that are included in the previous ce and ee releases
+while read -r file; do
+    if is_released "$file" "$prev_ce_tag" && is_released "$file" "$prev_ee_tag"; then
+        echo "deleting $file, released in $prev_ce_tag and $prev_ee_tag"
+        rm -f "$file"
+    fi
+done < <(find "$top_dir/changes/ce" -type f -name '*.md')
+
+## loop over files in $top_dir/changes/ee
+## and delete the ones taht are included in the previous ee release
+while read -r file; do
+    if is_released "$file" "$prev_ee_tag"; then
+        echo "deleting $file, released in $prev_ee_tag"
+        rm -f "$file"
+    fi
+done < <(find "$top_dir/changes/ee" -type f -name '*.md')