dev-python/packaging: Use flit to ease bootstrap

Signed-off-by: Michał Górny <mgorny@gentoo.org>

dev-python/packaging/packaging-21.3-r2.ebuild

@@ -0,0 +1,49 @@
+# Copyright 1999-2022 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+# please keep this ebuild at EAPI 7 -- sys-apps/portage dep
+EAPI=7
+
+DISTUTILS_USE_PEP517=flit
+PYTHON_COMPAT=( python3_{8..10} pypy3  )
+inherit distutils-r1
+
+DESCRIPTION="Core utilities for Python packages"
+HOMEPAGE="
+	https://github.com/pypa/packaging/
+	https://pypi.org/project/packaging/"
+SRC_URI="
+	https://github.com/pypa/packaging/archive/${PV}.tar.gz -> ${P}.gh.tar.gz"
+
+SLOT="0"
+LICENSE="|| ( Apache-2.0 BSD-2 )"
+KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~m68k ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86 ~x64-cygwin ~amd64-linux ~x86-linux ~ppc-macos ~x64-macos ~sparc-solaris ~sparc64-solaris ~x64-solaris ~x86-solaris"
+
+RDEPEND="
+	>=dev-python/pyparsing-3.0.6[${PYTHON_USEDEP}]
+"
+DEPEND="
+	test? (
+		dev-python/pretend[${PYTHON_USEDEP}]
+	)
+"
+
+distutils_enable_tests pytest
+
+src_configure() {
+	# write a custom pyproject.toml to ease setuptools bootstrap
+	cat > pyproject.toml <<-EOF || die
+		[build-system]
+		requires = ["flit_core >=3.2,<4"]
+		build-backend = "flit_core.buildapi"
+
+		[project]
+		name = "packaging"
+		dynamic = ["version"]
+		description = "More routines for operating on iterables, beyond itertools"
+	EOF
+}
+
+python_test() {
+	epytest --capture=no
+}