gnu: python-docutils: Update to 0.21.2.

This change updates python-docutils to the latests version and pins some
older packages on 0.19 to resolve build documentation issue which uses
rst2man.

* gnu/packages/python-xyz.scm (python-docutils): Update to 0.21.2.
[build-system]: Use pyproject.
[arguments] <phases>: Do not overwrite 'check use {#:test-backend} and
{#:test-flags}.
[native-inputs]: Add python-flit-core.

(python-docutils-0.16)[native-inputs]: Add python-wheel.

(python-docutils-0.19): New variable.

* gnu/packages/diffoscope.scm (trydiffoscope) [native-inputs]: Remove
python-docutils; add python-docutils-0.19.
* gnu/packages/gtk.scm (gtk): Likewise.
* gnu/packages/linux.scm (rdma-core): Likewise.
* gnu/packages/power.scm (apcupsd): Likewise.
* gnu/packages/version-control.scm (cgit): Likewise.
* gnu/packages/virtualization.scm (ganeti)) Likewise.

Change-Id: If58b9b12732347245e66e3c2cb5e67b0a8450913

gnu/packages/python-xyz.scm

@@ -8553,21 +8553,20 @@ Google and Numpydoc format.")
 (define-public python-docutils
   (package
     (name "python-docutils")
-    (version "0.19")
-    (source (origin
-              (method url-fetch)
-              (uri (pypi-uri "docutils" version))
-              (sha256
-               (base32
-                "1rprvir116g5rz2bgzkzgyn6mv0z8582rz7bgxbpy2y3adkmm69k"))))
-    (build-system python-build-system)
+    (version "0.21.2")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (pypi-uri "docutils" version))
+       (sha256
+        (base32 "0vwqzbmzdvwx23myx4cg8s8mdkrqnfxpa9yi7jm2s66z5rrihsrs"))))
+    (build-system pyproject-build-system)
     (arguments
-     '(#:phases (modify-phases %standard-phases
-                  (replace 'check
-                    (lambda* (#:key tests? #:allow-other-keys)
-                      (if tests?
-                          (invoke "python" "test/alltests.py")
-                          (format #t "test suite not run~%")))))))
+     (list
+      #:test-backend #~'custom
+      #:test-flags #~(list "test/alltests.py")))
+    (native-inputs
+     (list python-flit-core))
     (home-page "https://docutils.sourceforge.net/")
     (synopsis "Python Documentation Utilities")
     (description
@@ -8595,7 +8594,21 @@ via commands such as @command{rst2man}, as well as supporting Python code.")
     ;; tests contain Python 2 syntax.
     (arguments '(#:tests? #false))
     (native-inputs
-     (list python-setuptools))))
+     (list python-setuptools python-wheel))))
+
+(define-public python-docutils-0.19
+  (hidden-package
+   (package
+     (inherit python-docutils)
+     (version "0.19")
+     (source (origin
+               (method url-fetch)
+               (uri (pypi-uri "docutils" version))
+               (sha256
+                (base32
+                 "1rprvir116g5rz2bgzkzgyn6mv0z8582rz7bgxbpy2y3adkmm69k"))))
+     (native-inputs
+      (list python-setuptools python-wheel)))))
 
 (define-public python-docx
   (package
@@ -39924,7 +39937,7 @@ path.")
     (native-inputs
      (list perl-image-exiftool
            python-dateutil
-           python-docutils
+           python-docutils-0.19
            python-jinja2
            python-markdown
            python-pillow