bug#27572: simultaneous installation of python2 and python3 fails

[ludo@gnu.org (Ludovic Courtès)]

Hello Diego,

Diego Nicola Barbato <dnbarbato@posteo.de> skribis:

> When running the command "guix pull && guix package -i python@2 python"
> instead of installing the latest version of python2 and python3, as it
> used to do until about four weeks ago, guix gives following error
> message (hash values replaced with ...):
>
>   guix package: error: profile contains conflicting entries for python:out
>   guix package: error:   first entry: python@2.7.13:out /gnu/store/...-python-2.7.13
>   guix package: error:   second entry: python@3.5.3:out /gnu/store/...-python-3.5.3

Indeed, Guix now refuses to install two different versions or variants
of the same package since in general they would conflict.

In this particular case, they do not actually conflict, I think, since
python@3 provides executables prefixed by “3” whereas python@2 does not.

Perhaps we should rename “python” to “python2” or something like that?

In the meantime, I recommend using separate profiles for your Python 2
and Python 3 development environments.  Is that a viable option for you?

Thanks,
Ludo’.