dev-python/msgpack: version bump to 0.5.6.

Add native-extensions USE flag to conditionally disable C extensions.

Closes: https://github.com/gentoo/gentoo/pull/7176

dev-python/msgpack/Manifest

@@ -1,2 +1,3 @@
+DIST msgpack-0.5.6.tar.gz 138292 BLAKE2B 6a3b8472b785d77e142d21464b9e52c55166a8eff56009f63df5daa8cd5b6dbce4406a06ffa8d478cb44dfbdfab2f3b4b29cd11279ea82f67906b97d507f7eda SHA512 bdbd193bd3bd02e78d9c6e8d9d8fa687d13583dff2813bc77c5e6cbbe0d180765da3c9a80d176f9993589e35f548ad04973e3d523d0b6d41ef7916ecd86195aa
 DIST msgpack-python-0.4.8.tar.gz 113641 BLAKE2B d22efe13302e28d0701b95b2dc4cf4792f9e045efdf77b31ac5c6170b503c885c265ff63387fe76a1aa67b1624963aa26d76dffb15fc2cb10cfe672b59e71b99 SHA512 59e9c43be6b92e6d10f40999e0902c350137e67a83c43bb15b273eca856a6eb39f24b625b02b40188a9365ce3101f03bfa9aa3dfff56c5c3b551533942183481
 DIST msgpack-python-0.5.1.tar.gz 138953 BLAKE2B 1fb7e5be33992808319e1444ff7f84cc13f034e60ce0ef2f72161bd4ccd0cd1ede27382bc1f365f268557c8ffe503fd12de66eb5840e79760d818e7e2f67fdcd SHA512 e5172e20bb25d2e12ba34ad2805ba4ea0776397986e8bf8e26d21353f57a2dba59a9c6669c817e4e91d5801558a50f95d81e02343f8f0292a01ec5d822fba61c

dev-python/msgpack/metadata.xml

@@ -9,4 +9,10 @@
     <remote-id type="pypi">msgpack-python</remote-id>
     <remote-id type="github">msgpack/msgpack-python</remote-id>
   </upstream>
+  <use>
+    <flag name="native-extensions">
+      Compiles native "C" extensions (speedups, instead of using python
+      fallback code).
+    </flag>
+  </use>
 </pkgmetadata>

dev-python/msgpack/msgpack-0.5.6.ebuild

@@ -0,0 +1,41 @@
+# Copyright 1999-2018 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=6
+PYTHON_COMPAT=( python2_7 python3_{4,5,6} pypy )
+
+inherit distutils-r1
+
+DESCRIPTION="MessagePack (de)serializer for Python"
+HOMEPAGE="http://msgpack.org https://github.com/msgpack/msgpack-python/ https://pypi.python.org/pypi/msgpack/"
+SRC_URI="mirror://pypi/${PN:0:1}/${PN}/${P}.tar.gz"
+
+LICENSE="Apache-2.0"
+SLOT="0"
+KEYWORDS="~amd64 ~arm ~arm64 ~ppc ~x86"
+IUSE="+native-extensions test"
+
+DEPEND="
+	dev-python/setuptools[${PYTHON_USEDEP}]
+	native-extensions? (
+		>=dev-python/cython-0.16[${PYTHON_USEDEP}]
+	)
+	test? (
+		dev-python/six[${PYTHON_USEDEP}]
+		dev-python/pytest[${PYTHON_USEDEP}]
+	)
+"
+
+python_prepare_all() {
+	# Remove pre-generated cython files
+	rm msgpack/{_packer,_unpacker}.cpp || die
+
+	if ! use native-extensions ; then
+		sed -i -e "/have_cython/s:True:False:" ./setup.py || die
+	fi
+	distutils-r1_python_prepare_all
+}
+
+python_test() {
+	py.test -v test || die "Tests fail with ${EPYTHON}"
+}