Merge pull request #23 from infosiftr/i386

Update Travis to also test i386 variants

Author: tianon

.travis.yml

@@ -4,13 +4,21 @@ services: docker
 env:
   - VARIANT=debian
   - VARIANT=alpine
+  - VARIANT=debian ARCH=i386
+  - VARIANT=alpine ARCH=i386
 
 install:
   - git clone https://github.com/docker-library/official-images.git ~/official-images
 
 before_script:
   - env | sort
   - image="memcached:$VARIANT"
+  - |
+    if [ -n "$ARCH" ]; then
+        from="$(awk '$1 == toupper("FROM") { print $2 }' "$VARIANT/Dockerfile")"
+        docker pull "$ARCH/$from"
+        docker tag "$ARCH/$from" "$from"
+    fi
 
 script:
   - travis_retry docker build -t "$image" "$VARIANT"