pyspark.sql.tests: is test_time_with_timezone a flaky test?

[Cheolsoo Park]

Hi devs,

For some reason, I keep getting this test failure (3 out of 4 builds) in my
PR <https://github.com/apache/spark/pull/7216>-

======================================================================
FAIL: test_time_with_timezone (__main__.SQLTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File
"/home/jenkins/workspace/SparkPullRequestBuilder/python/pyspark/sql/tests.py",
line 718, in test_time_with_timezone
    *self.assertEqual(now, now1)*
AssertionError: datetime.datetime(2015, 7, 12, 13, 18, 46, *504366*) !=
datetime.datetime(2015, 7, 12, 13, 18, 46, *504365*)

Jenkins builds-
https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/37100/console
https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/37092/console
https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/37081/console

I am aware that there was a hot fix for this test case, and I already have
it in the commit log-

commit 05ac023dc8d9004a27c2f06ee875b0ff3743ccdd

Author: Davies Liu <dav...@databricks.com>
Date:   Fri Jul 10 13:05:23 2015 -0700
    [HOTFIX] fix flaky test in PySpark SQL

I looked at the test code, and it seems that precision in microseconds is
lost somewhere in a round trip from Python to DataFrame. Can someone please
help me debug this error?

Thanks!
Cheolsoo