Older hacking depends on pep8, but pep8 module is replaced by
pycodestyle. This can be resolved by updating hackinng version.
This commit also fixes E117 (over-indented) and
W605 (invalid escape sequence) warnings.
pep8 is dropped from lower-constraints.txt as it is no longer used.
Change-Id: I3a8e3b0dedf9422e4db02b525b333d12ce012a95
f99c63f98a