gnu: unionfs-fuse: Enable tests.

* gnu/packages/linux.scm (unionfs-fuse)[arguments]: Replace 'check phase.
[native-inputs]: Add python, python-pytest.

gnu/packages/linux.scm

@@ -1521,8 +1521,16 @@ user-space processes.")
                (base32
                 "0hsn8l1iblvx27bpd4dvnvnbh9ri3sv2f9xzpsnfz3379kb7skgj"))))
     (build-system cmake-build-system)
+    (native-inputs
+     `(("python" ,python)
+       ("python-pytest" ,python-pytest)))
     (inputs `(("fuse" ,fuse)))
-    (arguments '(#:tests? #f))                    ; no tests
+    (arguments
+     '(#:phases
+       (modify-phases %standard-phases
+         (replace 'check
+           ;; Borrowed from the Makefile
+           (lambda _ (zero? (system* "python3" "-m" "pytest")))))))
     (home-page "https://github.com/rpodgorny/unionfs-fuse")
     (synopsis "User-space union file system")
     (description