py-treehash: Create new package (#10872)

var/spack/repos/builtin/packages/py-treehash/package.py

+# Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class PyTreehash(PythonPackage):
+    """Calculates a SHA256 (or, potentially, any other hashlib supported
+    function) "tree" hash, as used by e.g. Amazon Glacier."""
+
+    homepage = "https://github.com/jdswinbank/treehash"
+    url      = "https://pypi.io/packages/source/t/treehash/TreeHash-1.0.2.tar.gz"
+
+    version('1.0.2', sha256='fefcadd6a1e8ba2808897d776d5ae8bdae56ec3fe90ed385c1322357269f27a4')