[gentoo-user] Determine what's keeping Python 3.7 around?

[Grant Edwards]

I updated one of my systems a day or two ago, and Python 3.7 went away
as expected. Today, I'm updating another system and it is rebuilding
tons of stuff to target python 3.8 instead of 3.7, but it's keeping
3.7 and even wants to install a _new_ package -- and build it for
Python 3.7:

  [...]
  [nomerge       ] app-portage/gemato-16.2::gentoo  USE="gpg -test -tools" PYTHON_TARGETS="python3_8* (-pypy3) -python3_6 -python3_7* -python3_9"
  [nomerge       ]  dev-python/requests-2.24.0-r1::gentoo  USE="ssl -socks5 -test" PYTHON_TARGETS="python3_8* (-pypy3) -python3_6 -python3_7* -python3_9"
  [nomerge       ]   dev-python/cryptography-3.2.1::gentoo [3.2::gentoo] USE="-idna -libressl -test" PYTHON_TARGETS="python3_8* (-pypy3) -python3_6 -python3_7* -python3_9"
  [ebuild   R    ]    dev-python/six-1.15.0-r1::gentoo  USE="-doc -test" PYTHON_TARGETS="python3_8* (-pypy3) -python3_6 -python3_7* -python3_9" 0 KiB
  [ebuild     U  ]     dev-python/setuptools-50.3.0::gentoo [46.4.0-r3::gentoo] USE="-test" PYTHON_TARGETS="python3_8* (-pypy3) -python3_6 -python3_7* -python3_9 (-python2_7%*)" 2,119 KiB
  [ebuild  N     ]      dev-python/setuptools_scm-4.1.2-r1::gentoo  USE="-test" PYTHON_TARGETS="python3_7 python3_8 (-pypy3) -python3_6 -python3_9" 0 KiB
  [ebuild     U  ]      dev-python/certifi-10001-r1::gentoo [10001::gentoo] USE="-test" PYTHON_TARGETS="python3_8* (-pypy3) -python3_6 -python3_7* -python3_9 (-python2_7%*)" 0 KiB
  [...]
  Total: 109 packages (12 upgrades, 1 new, 96 reinstalls), Size of downloads: 924,708 KiB

How do I figure out why setuptools_scm is being built with the Python
3.7 target?

There are no python targets specified in /etc/portage/*

--
Grant