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.

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

./test/testall.py:23: DeprecationWarning: invalid escape sequence \.
  ver_bits = re.split("\.|[^\d]", ver_str, 2)[:2]
./lib/markdown2.py:449: DeprecationWarning: invalid escape sequence \s
  "(.*:\s+>\n\s+[\S\s]+?)(?=\n\w+\s*:\s*\w+\n|\Z)", re.MULTILINE)
./lib/markdown2.py:2167: DeprecationWarning: invalid escape sequence \w
  _incomplete_tags_re = re.compile("<(/?\w+[\s/]+?)")