Fails on pyup comments in requirements file

[peterbe]

E.g.

▶ hashin --dry-run -u -r requirements/default.txt
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/packaging/requirements.py", line 93, in __init__
    req = REQUIREMENT.parseString(requirement_string)
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 1632, in parseString
    raise exc
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 1622, in parseString
    loc, tokens = self._parse( instring, 0 )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
    loc,tokens = self.parseImpl( instring, preloc, doActions )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 3395, in parseImpl
    loc, exprtokens = e._parse( instring, loc, doActions )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
    loc,tokens = self.parseImpl( instring, preloc, doActions )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 3717, in parseImpl
    return self.expr._parse( instring, loc, doActions, callPreParse=False )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 1379, in _parseNoCache
    loc,tokens = self.parseImpl( instring, preloc, doActions )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 3378, in parseImpl
    loc, resultlist = self.exprs[0]._parse( instring, loc, doActions, callPreParse=False )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 1383, in _parseNoCache
    loc,tokens = self.parseImpl( instring, preloc, doActions )
  File "/usr/local/lib/python3.6/site-packages/pyparsing.py", line 2689, in parseImpl
    raise ParseException(instring, loc, self.errmsg, self)
pyparsing.ParseException: Expected W:(abcd...) (at char 4), (line:1, col:5)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/bin/hashin", line 11, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.6/site-packages/hashin.py", line 736, in main
    interactive=args.interactive,
  File "/usr/local/lib/python3.6/site-packages/hashin.py", line 104, in run
    req = Requirement(line.split("\\")[0])
  File "/usr/local/lib/python3.6/site-packages/packaging/requirements.py", line 97, in __init__
    requirement_string[e.loc:e.loc + 8]))
packaging.requirements.InvalidRequirement: Invalid requirement, parse error at "'# pyup: '"

Not sure which it's failing one. This one or this one or both. Should be easy to reproduce.