[size-report] checkout pull request head (#11724)

script/check-size

@@ -32,7 +32,7 @@ set -euo pipefail
 OT_TMP_DIR=/tmp/ot-size-report
 readonly OT_TMP_DIR
 
-OT_SHA_NEW=${GITHUB_SHA:-$(git rev-parse HEAD)}
+OT_SHA_NEW="$(git rev-parse HEAD)"
 readonly OT_SHA_NEW
 
 OT_SHA_OLD="${OT_SHA_OLD:-$(git cat-file -p "${OT_SHA_NEW}" | grep 'parent ' | head -n1 | cut -d' ' -f2)}"

script/git-tool

@@ -54,6 +54,14 @@ get_pr_body()
 {
     local pr
 
+    if [[ -z ${PR_BODY+x} ]]; then
+        echo 'PR_BODY is not set' >&2
+    else
+        echo 'PR_BODY is set' >&2
+        echo "${PR_BODY}"
+        return 0
+    fi
+
     [[ ${GITHUB_ACTIONS+x} && ${GITHUB_REF-} =~ ^refs/pull/[0-9]+/merge ]] || {
         echo 'Not a pull request.' >&2
         return 0