Python dependencies for ports requiring Python 3

[Andrew Berg]

On 2016.04.03 07:36, Raphael Kubo da Costa wrote:
> Hi, everyone,
>
> I've been helping get archivers/py-borgbackup (bug 207715) committed for
> a while now.
>
> The last remaining blocker is the fact that the port has
> USES=python:3.4+ and depends on other Python ports, namely
> devel/py-setuptools_scm, devel/py-msgpack-python and devel/py-llfuse.
> This means the port will try to require/install the Python 3 versions of
> those ports which are not built by default and not present in Poudriere
> builds if one does not explicitly build Python 3 packages.
This is a ports limitation that would be overcome by support for variants[1]. 
However, it is uncertain when all of the little issues blocking variants 
support will be resolved. The dependency problem you mention is the same reason 
that many other ports (e.g. Samba) cannot be built when the default is Python 
3. Kubilay's suggestion to create py3- ports is mainly a workaround to give you 
something close enough to variants that would allow this. These ports would 
need to be created, maintained, and then culled when we have proper support for 
variants. The alternative would be to simply wait until we have variants support.

[1] https://reviews.freebsd.org/D5563