temporary yapf mod

Author: richardliaw

.travis/yapf.sh

@@ -11,19 +11,10 @@ builtin cd "$ROOT"
 
 yapf \
     --style "$ROOT/.style.yapf" \
-    --in-place --recursive --parallel \
+    --diff --recursive --parallel \
     --exclude 'python/ray/cloudpickle' \
     --exclude 'python/ray/dataframe' \
     --exclude 'python/ray/rllib' \
     -- \
     'test' 'python'
 
-if ! git diff --quiet; then
-    echo 'Reformatted staged files. Please review and stage the changes.'
-    echo 'Files updated:'
-    echo
-
-    git --no-pager diff --name-only
-
-    exit 1
-fi