Revert "Reproduce DataFrameReaderWriterSuite failure"

This reverts commit 7680aa0.

Author: zsxwing

dev/run-tests

@@ -20,8 +20,4 @@
 FWDIR="$(cd "`dirname $0`"/..; pwd)"
 cd "$FWDIR"
 
-set -e
-for i in `seq 1 300`; do
-    build/sbt -Pyarn -Phadoop-2.4 -Dhadoop.version=2.4.0 "project sql" test
-done
-# exec python -u ./dev/run-tests.py "$@"
+exec python -u ./dev/run-tests.py "$@"