gnu: Add python-rq-scheduler.

* gnu/packages/databases.scm (python-rq-scheduler): New public variable.

gnu/packages/databases.scm

@@ -3113,6 +3113,44 @@ is designed to have a low barrier to entry.")
 (define-public python2-rq
   (package-with-python2 python-rq))
 
+(define-public python-rq-scheduler
+  (package
+    (name "python-rq-scheduler")
+    (version "0.10.0")
+    (home-page "https://github.com/rq/rq-scheduler")
+    (source (origin
+              (method git-fetch)
+              (uri (git-reference
+                    (url home-page)
+                    (commit (string-append "v" version))))
+              (file-name (git-file-name name version))
+              (sha256
+               (base32
+                "0xg6yazqs5kbr2ayvhvljs1h5vgx5k5dds613fmhswln7gglf9hk"))))
+    (build-system python-build-system)
+    (arguments
+     '(#:phases (modify-phases %standard-phases
+                  (add-before 'check 'start-redis
+                    (lambda _
+                      (invoke "redis-server" "--daemonize" "yes")))
+                  (replace 'check
+                    (lambda _
+                      (substitute* "run_tests.py"
+                        (("/usr/bin/env")
+                         (which "env")))
+                      (invoke "./run_tests.py"))))))
+    (native-inputs
+     `(("redis" ,redis)
+       ("which" ,which)))
+    (propagated-inputs
+     `(("python-croniter" ,python-croniter)
+       ("python-rq" ,python-rq)))
+    (synopsis "Job scheduling capabilities for RQ (Redis Queue)")
+    (description
+     "This package provides job scheduling capabilities to @code{python-rq}
+(Redis Queue).")
+    (license license:expat)))
+
 (define-public python-trollius-redis
   (package
     (name "python-trollius-redis")