bin-install fails for non-default python versions

[Greg Troxel <gdt%lexort.com@localhost>]

I am trying to build wip/py-homeassistant for 3.13, because Home
Assistant is removing 3.12 support in the 2025.2 release.

I have

  DEPENDS_TARGET?=        bin-install clean

in general, because I like "pkgin ar" to get rid of stuff I don't want,
to tidy, and to avoid rebuilding things I won't need, while not having
to rebuild them on the next build of some package.


$ make
===> Installing dependencies for py313-homeassistant-0.07
==========================================================================
The following variables will affect the build process of this package,
py313-homeassistant-0.07.  Their current value is shown below:

        * PYTHON_VERSION_DEFAULT = 312
        * SSLBASE = /usr
        * SSLCERTBUNDLE (not defined)
        * SSLCERTS = /etc/openssl/certs
        * SSLDIR = /etc/openssl
        * SSLKEYS = /etc/openssl/private

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

        * PYPACKAGE = python313

You may want to abort the process now with CTRL-C and change the value
of variables in the first group before continuing.  Be sure to run
`/usr/bin/make clean' after the changes.
==========================================================================
=> Tool dependency mktools-[0-9]*: found mktools-20220614
=> Tool dependency cwrappers>=20150314: found cwrappers-20220403
=> Full dependency py313-virtualenv-[0-9]*: NOT found
=> Verifying bin-install clean for ../../devel/py-virtualenv
===> Binary install for py313-virtualenv-[0-9]*
=> Becoming ``root'' to make su-do-bin-install (sudo)
PKGWILDCARD <py312-virtualenv-[0-9]*>
ERROR: py312-virtualenv-20.28.0 is already installed - perhaps an older version?
ERROR: If so, you may wish to ``pkg_delete py312-virtualenv-20.28.0'' and install
ERROR: this package again by ``/usr/bin/make bin-install'' to upgrade it properly.
*** Error code 1

It seems like somehow the required for py313- is being lost and it's
flipping back to py312.  (PKGWILDCARD line is just echo.)

I am reading code, but if anybody understands a fix would be great.