subprocess.run AttributeError occurred in Python 3.4

• 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).

Environment

• Poetry version: 0.12.17
• Python version: 3.4.8
• OS: Ubuntu 16.04.6 LTS in travis ci

https://travis-ci.org/HttpRunner/HttpRunner/jobs/557941936

Issue

Description

AttributeError occurred in Python 3.4, because the subprocess.run() function only exists in Python 3.5 and newer.

$ poetry install -v
                                          
[AttributeError]           
'module' object has no attribute 'run'  
                                          
Exception trace:
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/cleo/application.py in run() at line 94
   status_code = self.do_run(input_, output_)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/console/application.py in do_run() at line 88
   return super(Application, self).do_run(i, o)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/cleo/application.py in do_run() at line 197
   status_code = command.run(input_, output_)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/console/commands/command.py in run() at line 77
   return super(BaseCommand, self).run(i, o)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/cleo/commands/base_command.py in run() at line 136
   self.initialize(input_, output_)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/console/commands/env_command.py in initialize() at line 18
   current_env = Env.get(self.poetry.file.parent)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/utils/env.py in get() at line 227
   return VirtualEnv(prefix, base_prefix)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/utils/env.py in __init__() at line 483
   self._base = Path(self.run("python", "-", input_=GET_BASE_PREFIX).strip())
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/utils/env.py in run() at line 539
   return super(VirtualEnv, self).run(bin, *args, **kwargs)
 /home/travis/virtualenv/python3.4.8/lib/python3.4/site-packages/poetry/utils/env.py in run() at line 373
   output = subprocess.run(
install [--no-dev] [--dry-run] [-E|--extras EXTRAS] [--develop DEVELOP]
The command "poetry install -v" failed and exited with 1 during .

How to Reproduce

View the detail logs in travis CI job.

[debugtalk]

Python 3.4 was EOL 2019-03-18. See here: https://devguide.python.org/devcycle/#end-of-life-branches

@bertjwregeer I agree. Thus the README should say Poetry supports 2.7 and 3.5+😁

_{Sent with GitHawk}

[stale[bot]]

Closing this issue automatically because it has not had any activity since it has been marked as stale. If you think it is still relevant and should be addressed, feel free to open a new one.