Fix Python 3 TypeError in contrib.hive.HiveTableTarget.exists()

Closes #1012

luigi/contrib/hive.py

@@ -68,7 +68,7 @@ def run_hive(args, check_return_code=True):
  if check_return_code and p.returncode != 0:
  raise HiveCommandError("Hive command: {0} failed with error code: {1}".format(" ".join(cmd), p.returncode),
  stdout, stderr)
- return stdout
+ return stdout.decode('utf-8')
 
 
 def run_hive_cmd(hivecmd, check_return_code=True):

test/contrib/hive_test.py

@@ -32,7 +32,7 @@ class HiveTest(unittest.TestCase):
  def mock_hive_cmd(self, args, check_return=True):
  self.last_hive_cmd = args
  self.count += 1
- return "statement{0}".format(self.count)
+ return six.u("statement{0}".format(self.count))
 
  def setUp(self):
  self.run_hive_cmd_saved = luigi.contrib.hive.run_hive
@@ -262,7 +262,7 @@ def test_run_hive_command(self, popen):
  # I'm testing this again to check the return codes
  # I didn't want to tear up all the existing tests to change how run_hive is mocked
  comm = mock.Mock(name='communicate_mock')
- comm.return_value = "some return stuff", ""
+ comm.return_value = six.b("some return stuff"), ""
 
  preturn = mock.Mock(name='open_mock')
  preturn.returncode = 0
@@ -275,7 +275,7 @@ def test_run_hive_command(self, popen):
  preturn.returncode = 17
  self.assertRaises(luigi.contrib.hive.HiveCommandError, luigi.contrib.hive.run_hive, ["blah", "blah"])
 
- comm.return_value = "", "some stderr stuff"
+ comm.return_value = six.b(""), "some stderr stuff"
  returned = luigi.contrib.hive.run_hive(["blah", "blah"], False)
  self.assertEqual("", returned)