python3Packages.python-hglib: init at 2.6.1

This is required for glean-sdk python module. It uses 2.6.1 specifically.
We'd need to relax the requirement and update it to 2.6.2 later.

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

@@ -0,0 +1,29 @@
+{ lib
+, python3Packages
+}:
+
+python3Packages.buildPythonPackage rec {
+  pname = "python-hglib";
+  # https://bugzilla.mozilla.org/show_bug.cgi?id=1741686
+  version = "2.6.1";
+
+  src = python3Packages.fetchPypi {
+    inherit pname version;
+    sha256 = "sha256-fB+gy00zLdbshAmwR4fOukYj6X+zeGVvfKsLmWxso7I=";
+  };
+
+  buildInputs = [
+  ];
+
+  # attempts to create a temporary `HGTMP` folder
+  doCheck = false;
+
+  pythonImportsCheck = [ "hglib" ];
+
+  meta = with lib; {
+    description = "Library with a fast, convenient interface to Mercurial. It uses Mercurial’s command server for communication with hg.";
+    homepage = "https://www.mercurial-scm.org/wiki/PythonHglibs";
+    license = licenses.mit;
+    maintainers = [ maintainers.kvark ];
+  };
+}