bugfix.

.github/workflows/docker.yml

@@ -5,23 +5,23 @@ name: Docker
 on:
   push:
 
-# A workflow run is made up of one or more jobs that can run sequentially or in parallel
 jobs:
-  # This workflow contains a single job called "build"
   build:
-    # The type of runner that the job will run on
     runs-on: ubuntu-latest
 
-    # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
-    # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
     - uses: actions/checkout@v2
 
+    - name: Extract branch name
+      shell: bash
+      run: echo "##[set-output name=branch;]$(echo ${GITHUB_REF#refs/heads/})"
+      id: extract_branch
+
     - name: Build and push Docker images
       uses: docker/[email protected]
       with:
         username: ${{ secrets.DOCKER_USERNAME }}
         password: ${{ secrets.DOCKER_PASSWORD }}
         repository: overtrue/phplint
-        tags: ${GITHUB_REF#refs/heads/}
+        tags: ${{ steps.extract_branch.outputs.branch }}