python36Packages.traitlets, pythonPackages.traitlets: 5.0.5 -> 4.3.3

Version 5.x of traitlets requires Python 3.7, so it doesn't build on Python
3.6.  This commit downgrades traitlets to 4.3.3 on Python versions older than
3.7 so that it can still be used.

3 files changed, 42 insertions, 4 deletions

diff --git a/pkgs/development/python-modules/traitlets/4.nix b/pkgs/development/python-modules/traitlets/4.nix
new file mode 100644
index 000000000000..bffd7c790bea
--- /dev/null
+++ b/pkgs/development/python-modules/traitlets/4.nix
@@ -0,0 +1,36 @@
+{ lib
+, buildPythonPackage
+, fetchPypi
+, glibcLocales
+, pytest
+, mock
+, ipython_genutils
+, decorator
+, enum34
+, pythonOlder
+, six
+}:
+
+buildPythonPackage rec {
+  pname = "traitlets";
+  version = "4.3.3";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "d023ee369ddd2763310e4c3eae1ff649689440d4ae59d7485eb4cfbbe3e359f7";
+  };
+
+  checkInputs = [ glibcLocales pytest mock ];
+  propagatedBuildInputs = [ ipython_genutils decorator six ] ++ lib.optional (pythonOlder "3.4") enum34;
+
+  checkPhase = ''
+    LC_ALL="en_US.UTF-8" py.test
+  '';
+
+  meta = {
+    description = "Traitlets Python config system";
+    homepage = "http://ipython.org/";
+    license = lib.licenses.bsd3;
+    maintainers = with lib.maintainers; [ ];
+  };
+}
diff --git a/pkgs/development/python-modules/traitlets/default.nix b/pkgs/development/python-modules/traitlets/default.nix
index 5d304c61f5cb..3bc05897af66 100644
--- a/pkgs/development/python-modules/traitlets/default.nix
+++ b/pkgs/development/python-modules/traitlets/default.nix
@@ -1,6 +1,5 @@
 { lib
 , buildPythonPackage
-, isPy27
 , fetchPypi
 , glibcLocales
 , pytest
@@ -15,7 +14,7 @@
 buildPythonPackage rec {
   pname = "traitlets";
   version = "5.0.5";
-  disabled = isPy27;
+  disabled = pythonOlder "3.7";
 
   src = fetchPypi {
     inherit pname version;
@@ -23,7 +22,7 @@ buildPythonPackage rec {
   };
 
   checkInputs = [ glibcLocales pytest mock ];
-  propagatedBuildInputs = [ ipython_genutils decorator six ] ++ lib.optional (pythonOlder "3.4") enum34;
+  propagatedBuildInputs = [ ipython_genutils decorator six ];
 
   checkPhase = ''
     LC_ALL="en_US.UTF-8" py.test
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 447bbcbbdbec..421aca7033a7 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -7437,7 +7437,10 @@ in {
 
   trackpy = callPackage ../development/python-modules/trackpy { };
 
-  traitlets = callPackage ../development/python-modules/traitlets { };
+  traitlets = if pythonOlder "3.7" then
+    callPackage ../development/python-modules/traitlets/4.nix { }
+  else
+    callPackage ../development/python-modules/traitlets { };
 
   traits = callPackage ../development/python-modules/traits { };