ipython can't be installed with python 2.7, even when an exact version is specified

• 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).

Similar to #151 , but not sure how to resolve it at all. The command “poetry add -vvv ipython” fails with a virtualenv on python 2.7 .

• OS version and name: Linux 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt9-2 (2015-04-13) x86_64 GNU/Linux
• Poetry version: 0.11.4
• Link of a Gist with the contents of your pyproject.toml file: https://gist.github.com/buriy/8db57876a178bb2a34095c1d9ca8d388

Issue

$ poetry update -vvv

[SolverProblemError]
The current supported Python versions are 2.7.9
Because no versions of ipython match !=6.5.0
and ipython (6.5.0) requires Python >=3.3, ipython is forbidden.
So, because myproject depends on ipython (*), version solving failed.

P.S. Somehow “poetry update” works with exact version specified: ipython = “5.8.0” but “poetry install” doesn’t get it.

[buriy]

Yes, problem is not only with that last ipython for the user python version isn’t detected correctly, but also that no user should get any cryptic or humiliating messages at all. Right now the dialog looks like this: – install ipython – no, i won’t, you’re doing it all wrong.

[sdispater]

@buriy I see what you mean. I agree we should improve the behavior of the add command and select a constraint that satisfies the current project Python constraint.