Poetry raises a [TypeError]'encoding' is an invalid keyword argument for this function when running in Python2.7 virtual environment

• I am on the latest Poetry version.

• I have searched the issues of this repo and believe that this is not a duplicate.

• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Ubuntu 18.04

• Poetry version: 0.12.17

• Link of a Gist with the contents of your pyproject.toml file: I am not allowed due to company rules

Issue

When running poetry (command: poetry update) from within a 2.7 virtual environment while parsing a package defined as a git repository the following error occurs:

[TypeError]                                     
'encoding' is an invalid keyword argument for this function  

when run with the -vvv option I get the following:

Exception trace:
 /home/mroscoe/.poetry/lib/poetry/_vendor/py2.7/cleo/application.py in run() at line 94
   status_code = self.do_run(input_, output_)
 /home/mroscoe/.poetry/lib/poetry/console/application.py in do_run() at line 88
   return super(Application, self).do_run(i, o)
 /home/mroscoe/.poetry/lib/poetry/_vendor/py2.7/cleo/application.py in do_run() at line 197
   status_code = command.run(input_, output_)
 /home/mroscoe/.poetry/lib/poetry/console/commands/command.py in run() at line 77
   return super(BaseCommand, self).run(i, o)
 /home/mroscoe/.poetry/lib/poetry/_vendor/py2.7/cleo/commands/base_command.py in run() at line 146
   status_code = self.execute(input_, output_)
 /home/mroscoe/.poetry/lib/poetry/_vendor/py2.7/cleo/commands/command.py in execute() at line 107
   return self.handle()
 /home/mroscoe/.poetry/lib/poetry/console/commands/update.py in handle() at line 41
   return installer.run()
 /home/mroscoe/.poetry/lib/poetry/installation/installer.py in run() at line 73
   self._do_install(local_repo)
 /home/mroscoe/.poetry/lib/poetry/installation/installer.py in _do_install() at line 290
   self._execute(op)
 /home/mroscoe/.poetry/lib/poetry/installation/installer.py in _execute() at line 306
   getattr(self, "_execute_{}".format(method))(operation)
 /home/mroscoe/.poetry/lib/poetry/installation/installer.py in _execute_install() at line 331
   self._installer.install(operation.package)
 /home/mroscoe/.poetry/lib/poetry/installation/pip_installer.py in install() at line 35
   self.install_git(package)
 /home/mroscoe/.poetry/lib/poetry/installation/pip_installer.py in install_git() at line 230
   self.install_directory(pkg)
 /home/mroscoe/.poetry/lib/poetry/installation/pip_installer.py in install_directory() at line 196
   with open(setup, "w", encoding="utf-8") as f:

I was able to resolve the issue by adding the following import to the pip_installer.py file:

from io import open

[v5y8]

I also ran into this issue, on Poetry version 1.0.5 on Ubuntu 18.04 and running poetry inside a conda environment.

Apparently this can be caused by an outdated msgback-python package documented here and here.

I was able to solve this by running pip install --upgrade --user msgpack-python.

[badrobit]

Yes it is still relevant and needs to be fixed