improve transpile-branch.sh script

(cherry picked from commit d4315671)

.github/workflows/transpile.yml

@@ -29,5 +29,5 @@ jobs:
       - run: npm ci
         if: steps.cache.outputs.cache-hit != 'true'
       - run: bash scripts/upgrade-safe/git-user-config.sh
-      - run: bash scripts/upgrade-safe/transpile-branch.sh master origin/master
+      - run: bash scripts/upgrade-safe/transpile-onto.sh master origin/master
       - run: git push origin master

scripts/upgrade-safe/transpile-branch.sh → scripts/upgrade-safe/transpile-onto.sh

@@ -3,26 +3,36 @@
 set -euo pipefail
 
 if [ $# -lt 1 ]; then
-  echo "usage: bash $0 <branch> [base]" >&2
+  echo "usage: bash $0 <target> [base]" >&2
   exit 1
 fi
 
 set -x
 
-branch="$1"
-base="${2:-}"
+target="$1"
+base="${2-}"
 
 bash scripts/upgrade-safe/transpile.sh
 
 commit="$(git rev-parse --short HEAD)"
+branch="$(git rev-parse --abbrev-ref HEAD)"
 
 git add contracts
-git checkout --orphan "$branch"
 
-if [ -n "$base" ]; then
+git checkout --quiet --detach
+
+if git rev-parse --quiet --verify "$target"; then
+  git reset --soft "$target"
+  git checkout "$target"
+else
+  if [ -n "$base" ]; then
     git reset --soft "$base"
+  fi
+  git checkout --orphan "$target"
 fi
 
-if ! git diff --cached --quiet; then
+if ! git diff --quiet --cached; then
   git commit -m "Transpile $commit"
 fi
+
+git checkout "$branch"