gnu: python2-setuptools: Downgrade to 41.0.1.

* gnu/packages/python-xyz.scm (python2-setuptools): Define older version
instead of inheriting from python-setuptools.
(python-setuptools)[properties]: Record python2-variant.

gnu/packages/python-xyz.scm

@@ -1181,10 +1181,54 @@ Python 3 support.")
     (license (list license:psfl        ; setuptools itself
                    license:expat       ; six, appdirs, pyparsing
                    license:asl2.0      ; packaging is dual ASL2/BSD-2
-                   license:bsd-2))))
+                   license:bsd-2))
+    (properties `((python2-variant . ,(delay python2-setuptools))))))
 
+;; Newer versions of setuptools no longer support Python 2.
 (define-public python2-setuptools
-  (package-with-python2 python-setuptools))
+  (package
+    (name "python2-setuptools")
+    (version "41.0.1")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (pypi-uri "setuptools" version ".zip"))
+       (sha256
+        (base32
+         "04sns22y2hhsrwfy1mha2lgslvpjsjsz8xws7h2rh5a7ylkd28m2"))
+       (modules '((guix build utils)))
+       (snippet
+        '(begin
+           ;; Remove included binaries which are used to build self-extracting
+           ;; installers for Windows.
+           ;; TODO: Find some way to build them ourself so we can include them.
+           (for-each delete-file (find-files "setuptools" "^(cli|gui).*\\.exe$"))
+           #t))))
+    (build-system python-build-system)
+    ;; FIXME: Tests require pytest, which itself relies on setuptools.
+    ;; One could bootstrap with an internal untested setuptools.
+    (arguments
+     `(#:tests? #f))
+    (native-inputs
+     `(("unzip" ,unzip)))
+    (home-page "https://pypi.org/project/setuptools/")
+    (synopsis
+     "Library designed to facilitate packaging Python projects")
+    (description
+     "Setuptools is a fully-featured, stable library designed to facilitate
+packaging Python projects, where packaging includes:
+Python package and module definitions,
+distribution package metadata,
+test hooks,
+project installation,
+platform-specific details,
+Python 3 support.")
+    ;; TODO: setuptools now bundles the following libraries:
+    ;; packaging, pyparsing, six and appdirs. How to unbundle?
+    (license (list license:psfl         ; setuptools itself
+                   license:expat        ; six, appdirs, pyparsing
+                   license:asl2.0       ; packaging is dual ASL2/BSD-2
+                   license:bsd-2))))
 
 ;; The setuptools provided by Python 3.7.4 is too new for Tensorflow.
 (define-public python-setuptools-for-tensorflow