pr head commit scenario

README.md

@@ -10,8 +10,7 @@ By default, the repository that triggered the workflow is checked-out, for the r
 
 Refer [here](https://help.github.com/en/articles/events-that-trigger-workflows) to learn which commit `$GITHUB_SHA` points to for different events.
 
-# What's new
-
+Changes in V2:
 - Improved fetch performance
   - The default behavior now fetches only the SHA being checked-out
 - Script authenticated git commands
@@ -39,9 +38,8 @@ Refer [here](https://github.com/actions/checkout/blob/v1/README.md) for previous
     # Default: ${{ github.repository }}
     repository: ''
 
-    # The branch, tag or SHA to checkout.  When checking out the repository that
-    # triggered a workflow, this defaults to the reference or SHA for that event.
-    # Otherwise, defaults to `master`.
+    # Ref to checkout (SHA, branch, tag). For the repository that triggered the
+    # workflow, defaults to the ref/SHA for the event. Otherwise defaults to master.
     ref: ''
 
     # Access token for clone repository
@@ -89,7 +87,7 @@ Refer [here](https://github.com/actions/checkout/blob/v1/README.md) for previous
 ```yaml
 - uses: actions/checkout@v2-beta
   with:
-    ref: ${{ github.event.after }}
+    ref: refs/pull/${{ github.event.number }}/head
 ```
 
 # License

action.yml

@@ -1,14 +1,13 @@
 name: 'Checkout'
-description: 'Checkout a Git repository at a particular version'
+description: 'Checkout a Git repository'
 inputs: 
   repository:
     description: 'Repository name with owner. For example, actions/checkout'
     default: ${{ github.repository }}
   ref:
     description: >
-      The branch, tag or SHA to checkout.  When checking out the repository
-      that triggered a workflow, this defaults to the reference or SHA for
-      that event.  Otherwise, defaults to `master`.
+      Ref to checkout (SHA, branch, tag). For the repository that triggered the
+      workflow, defaults to the ref/SHA for the event. Otherwise defaults to master.
   token:
     description: 'Access token for clone repository'
     default: ${{ github.token }}
@@ -26,4 +25,4 @@ inputs:
 runs:
   using: node12
   main: dist/index.js
-  post: dist/index.js
+  post: dist/index.js