branch as input for premerge workflow (#1683)

branch as input allowing manual workflow dispatch

.github/workflows/premerge.yml

@@ -2,6 +2,10 @@ name: Pre-merge
 
 on:
   workflow_dispatch:
+    inputs:
+      branch:
+        description: 'Branch to test'
+        required: true
   pull_request:
     paths:
       - scripts/cnode-helper-scripts/guild-deploy.sh
@@ -16,6 +20,7 @@ jobs:
         distro: [rockylinux, ubuntu]
     env:
       REGISTRY: ghcr.io
+      BRANCH: ${{ github.event.inputs.branch || '' }}
     if: github.event.pull_request.draft == false
     steps:
     - name: Provide additional free space
@@ -42,9 +47,13 @@ jobs:
     - uses: actions/checkout@v3
     - name: Define BRANCH, COMMIT and G_ACCOUNT in environment
       run: |
-        echo "BRANCH=${GITHUB_HEAD_REF}" >> $GITHUB_ENV
         echo "G_ACCOUNT=${GITHUB_REPOSITORY_OWNER,,}" >> $GITHUB_ENV
-        echo "COMMIT=$(git rev-parse --short "$GITHUB_SHA")" >> $GITHUB_ENV
+        if [[ -z ${{ env.BRANCH }} ]]; then
+          echo "BRANCH=${GITHUB_HEAD_REF}" >> $GITHUB_ENV
+          echo "COMMIT=$(git rev-parse --short "$GITHUB_SHA")" >> $GITHUB_ENV
+        else
+          echo "COMMIT=$(git rev-parse --short ${{ env.BRANCH }})" >> $GITHUB_ENV
+        fi
     - name: Testing guild-deploy.sh (IO fork of libsodium)
       run: |
         docker build . \