pkg/55007: Python build conflicts

[cryintothebluesky%gmail.com@localhost]

>Number:         55007
>Category:       pkg
>Synopsis:       Python build conflicts
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 23 10:00:00 +0000 2020
>Originator:     Sad Clouds
>Release:        
>Organization:
>Environment:
>Description:
Hello, I keep coming across build conflicts with Python packages. For example, I build various packages, which have dependencies on Python. One package requires py37-expat, since that's the default Python version, so it builds it. Then I'm building editors/vim-gtk2 which wants py27-expat, but it's trying to use the same build directory as py32-expat, so I get build conflict.

I probably need to clean object files for each package build and this could solve the issue. But wouldn't it be better to build different version of the same package under different build directories? I don't know much about Python or pkgsrc development, so no idea how easy this would be

Below is the actual example of a build conflict:
 

===> Installing dependencies for gtk2+-2.24.32nb11
==========================================================================
The supported build options for gtk2+ are:

        cups debug x11

The currently selected options are:

        x11

You can select which build options to use by setting PKG_DEFAULT_OPTIONS
or the following variable.  Its current value is shown:

        PKG_OPTIONS.gtk2 (not defined)

==========================================================================
==========================================================================
The following variables will affect the build process of this package,
gtk2+-2.24.32nb11.  Their current value is shown below:

        * PYTHON_VERSION_DEFAULT = 37

Based on these variables, the following variables have been set:

        * PYPACKAGE = python27

You may want to abort the process now with CTRL-C and change their value
before continuing.  Be sure to run `/usr/bin/make clean' after
the changes.
==========================================================================
=> Tool dependency glib2-tools-[0-9]*: found glib2-tools-2.62.3
=> Tool dependency libtool-base>=2.4.2nb9: found libtool-base-2.4.6nb2
=> Tool dependency gmake>=3.81: found gmake-4.2.1nb1
=> Tool dependency perl>=5.0: found perl-5.30.1
=> Tool dependency pkgconf-[0-9]*: found pkgconf-1.6.0
=> Build dependency x11-links>=1.31: found x11-links-1.31
=> Build dependency gobject-introspection>=1.34.0: found gobject-introspection-1.62.0
=> Build dependency cwrappers>=20150314: found cwrappers-20180325
=> Full dependency py27-expat-[0-9]*: NOT found
=> Verifying package-install for ../../textproc/py-expat
=> Bootstrap dependency digest>=20010302: found digest-20190127
===> Skipping vulnerability checks.
WARNING: No /usr/pkg/db/pkg/pkg-vulnerabilities file found.
WARNING: To fix run: `/usr/sbin/pkg_admin -K /usr/pkg/db/pkg fetch-pkg-vulnerabilities'.
===> Installing binary package of py27-expat-2.7.17
pkg_add: no pkg found for '/opt/netbsd_build/objects/textproc/py-expat/work/.packages/py27-expat-2.7.17.tgz', sorry.
pkg_add: 1 package addition failed
*** Error code 1


If I look in build directory:

# ls /opt/netbsd_build/objects/textproc/py-expat/work/.packages/
py37-expat-3.7.5.tgz


Really, build directory should be $PKG_NAME$PKG_VERSION to avoid these issues.
>How-To-Repeat:

>Fix: