sci-calculators/units: Fix shebang, convert to python-single-r1

Convert the ebuild to python-single-r1 to make it simpler (there is
really no need to use multi-impl for scripts). Correct the dependencies,
add missing REQUIRED_USE. Use python_is_python3 instead of some horrible
extglob logic. Disable Python at configure time instead of forcing it
off for make calls. Fix shebang on installed script.

sci-calculators/units/units-2.14-r1.ebuild

@@ -0,0 +1,51 @@
+# Copyright 1999-2017 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=6
+PYTHON_COMPAT=( python{2_7,3_4,3_5} )
+PYTHON_REQ_USE="xml"
+inherit eutils python-single-r1
+
+DESCRIPTION="Unit conversion program"
+HOMEPAGE="https://www.gnu.org/software/units/units.html"
+SRC_URI="mirror://gnu/${PN}/${P}.tar.gz"
+
+LICENSE="FDL-1.3 GPL-3"
+SLOT="0"
+KEYWORDS="~alpha ~amd64 ~arm ~hppa ~ppc ~ppc64 ~sparc ~x86 ~amd64-linux ~x86-linux"
+IUSE="+units_cur"
+
+RDEPEND="
+	sys-libs/readline:=
+	units_cur? (
+		dev-python/unidecode[${PYTHON_USEDEP}]
+		${PYTHON_DEPS}
+	)"
+DEPEND=${RDEPEND}
+
+REQUIRED_USE="units_cur? ( ${PYTHON_REQUIRED_USE} )"
+
+pkg_setup() {
+	use units_cur && python-single-r1_pkg_setup
+}
+
+src_configure() {
+	econf ac_cv_path_PYTHON=no
+}
+
+src_install() {
+	emake DESTDIR="${D}" install
+
+	dodoc ChangeLog NEWS README
+
+	# we're intentionally delaying this since 'make install' would
+	# get confused if we shove 'units_cur' there, and there is no real
+	# need to add more complexity for it
+	if use units_cur; then
+		local pyver
+		python_is_python3 && pyver=3 || pyver=2
+		sed -e "/^outfile/s|'.*'|'/usr/share/units/currency.units'|g" \
+			"units_cur${pyver}" > units_cur || die
+		python_doscript units_cur
+	fi
+}