Deprecation warning due to invalid escape sequences in Python 3.8

[tirkarthi]

Deprecation warnings are raised due to invalid escape sequences in Python 3.8 . Below is a log of the warnings raised during compiling all the python files. Using raw strings or escaping them will fix this issue. Similar to #1920

find . -iname '*.py'  | xargs -P 4 -I{} python -Wall -m py_compile {} 

./tests/logs/test_history.py:364: DeprecationWarning: invalid escape sequence \.
  '{(org\.apache\.hadoop\.mapred\.JobInProgress$Counter)'
./tests/logs/test_history.py:377: DeprecationWarning: invalid escape sequence \.
  '(org\.apache\.hadoop\.mapred\.FileOutputFormat$Counter)'
./tests/logs/test_history.py:422: DeprecationWarning: invalid escape sequence \.
  ' ERROR="java\.lang\.RuntimeException:'
./tests/logs/test_history.py:423: DeprecationWarning: invalid escape sequence \.
  ' PipeMapRed\.waitOutputThreads():'
./tests/logs/test_history.py:462: DeprecationWarning: invalid escape sequence \.
  ' HOSTNAME="172\.31\.18\.180" ERROR="" .\n',
./tests/logs/test_history.py:475: DeprecationWarning: invalid escape sequence \.
  ' ERROR="java\.lang\.RuntimeException:'
./tests/logs/test_history.py:476: DeprecationWarning: invalid escape sequence \.
  ' PipeMapRed\.waitOutputThreads():'
./tests/logs/test_history.py:561: DeprecationWarning: invalid escape sequence \.
  ' ERROR="java\.lang\.RuntimeException:'
./tests/logs/test_history.py:562: DeprecationWarning: invalid escape sequence \.
  ' PipeMapRed\.waitOutputThreads():'
./tests/test_protocol.py:368: DeprecationWarning: invalid escape sequence \c
  self.assertRoundTripOK(BytesValueProtocol(), None, b'\xe90\c1a')
./tests/test_protocol.py:403: DeprecationWarning: invalid escape sequence \c
  self.assertRoundTripOK(BytesProtocol(), b'caf\xe9', b'\xe90\c1a')
./tests/test_protocol.py:434: DeprecationWarning: invalid escape sequence \X
  self.assertRoundTripOK(TextProtocol(), u'caf\xe9', u'\Xe90\c1a')
./tests/test_conf.py:435: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '}),
./tests/test_conf.py:439: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '})
./tests/test_conf.py:520: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '}),
./tests/test_conf.py:524: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '})
./tests/test_conf.py:535: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '}),
./tests/test_conf.py:538: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '})
./tests/test_conf.py:632: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '}),
./tests/test_conf.py:636: DeprecationWarning: invalid escape sequence \w
  'PS1': '\w> '})
./tests/test_parse.py:134: DeprecationWarning: invalid escape sequence \s
  self.assertEqual(is_uri('C:\some\windows\path'), False)