python-xyz: Add python-ruamel.yaml.clib@0.2.6

This was taken directly from guix@a852a6d16868d7f28d416d5dbad3fabe31a46aed

rekahsoft-gnu/packages/python-xyz.scm

@@ -39,6 +39,7 @@
   #:use-module (gnu packages xml)
   #:use-module (guix packages)
   #:use-module (guix download)
+  #:use-module (guix hg-download)
   #:use-module (guix gexp)
   #:use-module (guix git-download)
   #:use-module (guix build-system python)
@@ -271,6 +272,44 @@ and has round-trip loaders and dumpers.  It supports comments.  Block
 style and key ordering are kept, so you can diff the source.")
     (license license:expat)))
 
+(define-public python-ruamel.yaml.clib-0.2.6
+  (package
+    (name "python-ruamel.yaml.clib")
+    (version "0.2.6")
+    (source
+      (origin
+        ;; pypi release code has cythonized code without corresponding source.
+        (method hg-fetch)
+        (uri (hg-reference
+               (url "http://hg.code.sf.net/p/ruamel-yaml-clib/code")
+               (changeset version)))
+        (file-name (string-append name "-" version "-checkout"))
+        (sha256
+         (base32
+          "05m3y7pjfbaarqbbgw1k6gs6cnnmxnwadjipxvw1aaaqk3s236cs"))
+        (modules '((guix build utils)))
+        (snippet
+         '(begin
+            (delete-file "_ruamel_yaml.c")))))
+    (build-system python-build-system)
+    (arguments
+     `(#:tests? #f  ; This package is split from python-ruamel.yaml and
+                    ; depends on modules from it for the test suite.
+       #:phases
+       (modify-phases %standard-phases
+         (delete 'sanity-check) ; Depends on python-ruamel.yaml
+         (add-after 'unpack 'cythonize-code
+           (lambda _
+             (invoke "cython" "_ruamel_yaml.pyx"))))))
+    (native-inputs
+     `(("python-cython" ,python-cython)))
+    (home-page "https://sourceforge.net/p/ruamel-yaml-clib/code/ci/default/tree")
+    (synopsis "C version of reader, parser and emitter for ruamel.yaml")
+    (description
+     "This package provides a C version of the reader, parser and emitter for
+@code{ruamel.yaml} derived from libyaml.")
+    (license license:expat)))
+
 ;; awscliv2 is a little bit of a packaging mess. They vendor multiple modified
 ;; forks of software also maintained by the same company. Namely:
 ;;