Invalid requirement: '–r'Traceback (most recent call last): File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/packaging/requirements.py", line 92, in __init__ req = REQUIREMENT.parseString(requirement_string) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 1617, in parseString raise exc File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 1607, in parseString loc, tokens = self._parse( instring, 0 ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 1379, in _parseNoCache loc,tokens = self.parseImpl( instring, preloc, doActions ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 3376, in parseImpl loc, exprtokens = e._parse( instring, loc, doActions ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 1379, in _parseNoCache loc,tokens = self.parseImpl( instring, preloc, doActions ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 3698, in parseImpl return self.expr._parse( instring, loc, doActions, callPreParse=False ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 1379, in _parseNoCache loc,tokens = self.parseImpl( instring, preloc, doActions ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 3359, in parseImpl loc, resultlist = self.exprs[0]._parse( instring, loc, doActions, callPreParse=False ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 1383, in _parseNoCache loc,tokens = self.parseImpl( instring, preloc, doActions ) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/pyparsing.py", line 2670, in parseImpl raise ParseException(instring, loc, self.errmsg, self)pip._vendor.pyparsing.ParseException: Expected W:(abcd...) (at char 0), (line:1, col:1) During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/req/req_install.py", line 82, in __init__ req = Requirement(req) File "/home/dev/.pyenv/versions/3.6.1/envs/env361/lib/python3.6/site-packages/pip/_vendor/packaging/requirements.py", line 96, in __init__ requirement_string[e.loc:e.loc + 8]))pip._vendor.packaging.requirements.InvalidRequirement: Invalid requirement, parse error at "'–r'"