Remove buildkit feature.

.travis.yml

@@ -44,10 +44,9 @@ before_script:
   - sudo apt-get update
   - apt-cache policy docker-ce
   - sudo apt-get install -y docker-ce="5:${DOCKER_VERSION}~3-0~ubuntu-$(lsb_release -cs)"
-  - docker version
   - sudo mv daemon.json /etc/docker/daemon.json
-  - sudo systemctl reload-or-restart docker
-  - sudo systemctl status docker
+  - sudo systemctl restart docker
+  - docker version
 
 # Run the build and packaging
 script:

daemon.json

@@ -1,6 +1,3 @@
 {
-  "mtu": 1460,
-  "features": {
-    "buildkit": true
-  }
+  "mtu": 1460
 }