python36Packages.ipython: 7.17 -> 7.16.1 (downgrade)

IPython versions 7.17 and higher don't support Python 3.6 anymore, so
this commit adds back the old expression for 7.16.1 from before
ba1038a98b for use in python36Packages
only.

    nix-repl> :b python36.withPackages (ps: [ ps.ipython ])
    builder for '/nix/store/q8v4f89xwv35a3idb9z345z6n3nzfycb-python3.6-ipython-7.17.0.drv' failed with exit code 1; last 10 log lines:
      Python 3.5 was supported with IPython 7.0 to 7.9.
      Python 3.6 was supported with IPython up to 7.16.

      See IPython `README.rst` file for more information:

          https://github.com/ipython/ipython/blob/master/README.rst

      Python sys.version_info(major=3, minor=6, micro=12, releaselevel='final', serial=0) detected.
    cannot build derivation '/nix/store/mhpdarp18z6skzswrl7sbgzv8hr4gwih-python3-3.6.12-env.drv': 1 dependencies couldn't be built
    [0 built (1 failed)]
    error: build of '/nix/store/mhpdarp18z6skzswrl7sbgzv8hr4gwih-python3-3.6.12-env.drv' failed

pkgs/development/python-modules/ipython/7.16.nix

@@ -0,0 +1,70 @@
+{ lib
+, stdenv
+, buildPythonPackage
+, fetchPypi
+, pythonOlder
+# Build dependencies
+, glibcLocales
+# Test dependencies
+, nose
+, pygments
+# Runtime dependencies
+, jedi
+, decorator
+, pickleshare
+, traitlets
+, prompt_toolkit
+, pexpect
+, appnope
+, backcall
+, fetchpatch
+}:
+
+buildPythonPackage rec {
+  pname = "ipython";
+  version = "7.16.1";
+  disabled = pythonOlder "3.6";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "9f4fcb31d3b2c533333893b9172264e4821c1ac91839500f31bd43f2c59b3ccf";
+  };
+
+  prePatch = lib.optionalString stdenv.isDarwin ''
+    substituteInPlace setup.py --replace "'gnureadline'" " "
+  '';
+
+  buildInputs = [ glibcLocales ];
+
+  checkInputs = [ nose pygments ];
+
+  propagatedBuildInputs = [
+    jedi
+    decorator
+    pickleshare
+    traitlets
+    prompt_toolkit
+    pygments
+    pexpect
+    backcall
+  ] ++ lib.optionals stdenv.isDarwin [appnope];
+
+  LC_ALL="en_US.UTF-8";
+
+  doCheck = false; # Circular dependency with ipykernel
+
+  checkPhase = ''
+    nosetests
+  '';
+
+  pythonImportsCheck = [
+    "IPython"
+  ];
+
+  meta = with lib; {
+    description = "IPython: Productive Interactive Computing";
+    homepage = "http://ipython.org/";
+    license = licenses.bsd3;
+    maintainers = with maintainers; [ bjornfor fridh ];
+  };
+}

pkgs/development/python-modules/ipython/default.nix

@@ -23,7 +23,7 @@
 buildPythonPackage rec {
   pname = "ipython";
   version = "7.17.0";
-  disabled = pythonOlder "3.6";
+  disabled = pythonOlder "3.7";
 
   src = fetchPypi {
     inherit pname version;

pkgs/top-level/python-packages.nix

@@ -2911,6 +2911,8 @@ in {
 
   ipython = if isPy27 then
     callPackage ../development/python-modules/ipython/5.nix { }
+  else if isPy36 then
+    callPackage ../development/python-modules/ipython/7.16.nix { }
   else
     callPackage ../development/python-modules/ipython { };