Incorrectly removes valid whitespace

[benf-wspdigital]

The U+000C FORM FEED character is valid white space. A line containing only U+000C at the end of a line is a valid blank line for Python::

$ printf "print('hello')\n\f\nprint('python')\n" > foo.py

$ wc foo.py
       3       2      33 foo.py

$ pycodestyle foo.py

$ python3 ./foo.py
hello
python

The autopep8 behaviour removes the valid whitespace::

$ autopep8 foo.py > foo.py.autopep8

$ wc foo.py.autopep8 
       3       2      32 foo.py.autopep8

$ grep -c '\f$' foo.py foo.py.autopep8 
foo.py:1
foo.py.autopep8:0

The pycodestyle tool correctly does not consider the U+000C character a trailing white space character (the W291 warning is not triggered).

So the autopep8 tool should also not remove that valid character from the line.

[hhatto]

@benf-wspdigital
Thanks for reporting 👍

fix in #376.