DOC: Fix PANDAS_VERSION in docs build

.github/workflows/docbuild-and-upload.yml

@@ -47,10 +47,33 @@ jobs:
     steps:
     - name: Set pandas version
       run: |
-        if [ -n "${{ github.event.inputs.version }}" ]; then
-          echo "PANDAS_VERSION=${{ github.event.inputs.version }}" >> "$GITHUB_ENV"
+        # tags include a `v` prefix.
+        tag_version_pat="^v\d+\.\d+\.\d+(rc\d+)?$"
+        version_pat="^\d+\.\d+\.\d+(rc\d+)?$"
+
+        if [[ -n "${{ github.event.inputs.version }}" ]]; then
+          PANDAS_VERSION="${{ github.event.inputs.version }}"
+        elif [[ "${{ github.event_name }}" == "push" && "$GITHUB_REF_NAME" =~ $tag_version_pat ]]; then
+          PANDAS_VERSION="${GITHUB_REF_NAME:1}"
         else
-          echo "PANDAS_VERSION=${GITHUB_REF_NAME:1}" >> "$GITHUB_ENV"
+          PANDAS_VERSION=""
+        fi
+        echo "PANDAS_VERSION=$PANDAS_VERSION" >> "$GITHUB_ENV"
+
+        if [[ "${{ github.event_name }}" == "push" && -n "$PANDAS_VERSION" ]]; then
+          PUBLISH_PROD="true"
+        elif [[ "${{ github.event.inputs.publish_prod }}" == "true" ]]; then
+          PUBLISH_PROD="true"
+        else
+          PUBLISH_PROD="false"
+        fi
+        echo "PUBLISH_PROD=$PUBLISH_PROD" >> "$GITHUB_ENV"
+
+        if [[ "$PUBLISH_PROD" == "true" ]] &&
+           [[ ! "$PANDAS_VERSION" =~ $version_pat ]]
+        then
+          echo "Invalid version $PANDAS_VERSION for publishing to prod."
+          exit 1
         fi
 
     - name: Checkout
@@ -105,7 +128,7 @@ jobs:
 
     - name: Upload prod docs
       run: rsync -az --delete doc/build/html/ web@${{ secrets.server_ip }}:/var/www/html/pandas-docs/version/${{ env.PANDAS_VERSION }}
-      if: ${{ (github.event_name == 'push' && startsWith(github.ref, 'refs/tags/')) || (inputs.publish_prod == 'true') }}
+      if: ${{ env.PUBLISH_PROD == 'true' }}
 
     - name: Move docs into site directory
       run: mv doc/build/html web/build/docs