Fixing GHA (#376)

* fix checkout step?

* Only push things if there's changes

* Have to checkout branch first

* try main instead?

* Try this

* Let's try being more exact about what commit

.github/workflows/render-preview.yml

@@ -19,9 +19,6 @@ jobs:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
       - name: checkout
         uses: actions/checkout@v2
-        with:
-          # get the full repo
-          fetch-depth: 0
 
       # We want a fresh run of the renders each time
       - name: Delete old docs/*
@@ -62,16 +59,16 @@ jobs:
       - name: Commit rendered bookdown files to development branch
         id: commit
         run: |
-          git checkout -b "preview-${{ github.event.pull_request.number }}"
           git config --local user.email "actions@github.com"
           git config --local user.name "GitHub Actions"
-          changes=$(git diff --name-only origin/main -- docs)
-          git add -A
-          git commit -m 'Render bookdown preview' || echo "No changes to commit"
-          git push --force origin "preview-${{ github.event.pull_request.number }}" || echo "No changes to push"
+          changes=$(git diff --name-only `git log --format="%H" -n 1 origin/main` -- docs)
 
           if [[ -n $changes ]]; then
             echo ::set-output name=changes::$(echo 'changes')
+            git checkout -b "preview-${{ github.event.pull_request.number }}"
+            git add -A
+            git commit -m 'Render bookdown preview'
+            git push --force origin "preview-${{ github.event.pull_request.number }}"
           else
             echo ::set-output name=changes::$(echo 'no_changes')
           fi

.github/workflows/style-and-sp-check.yml

@@ -21,9 +21,6 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
       - uses: actions/checkout@v2
-        # What branch to commit to: the one from the pull request
-        with:
-          ref: ${{ github.event.pull_request.head.ref }}
 
       - name: Run spell check
         id: spell_check_run