[gentoo-python] [PATCH] Support converting python[23] shebangs.

[Michał Górny]

For now, I assume that python2 can be converted to Python2 impls
implementations only, and python3 to Python3 impls.

Fixes: https://bugs.gentoo.org/show_bug.cgi?id=449674
---
 gx86/eclass/python-utils-r1.eclass | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/gx86/eclass/python-utils-r1.eclass b/gx86/eclass/python-utils-r1.eclass
index fe7a3e4..165a383 100644
--- a/gx86/eclass/python-utils-r1.eclass
+++ b/gx86/eclass/python-utils-r1.eclass
@@ -319,17 +319,33 @@ _python_rewrite_shebang() {
 	local f
 	for f; do
 		local shebang=$(head -n 1 "${f}")
+		local from
 		debug-print "${FUNCNAME}: path = ${f}"
 		debug-print "${FUNCNAME}: shebang = ${shebang}"
 
-		if [[ "${shebang} " != *'python '* ]]; then
+		if [[ "${shebang} " == *'python '* ]]; then
+			from=python
+		elif [[ "${shebang} " == *'python2 '* ]]; then
+			from=python2
+		elif [[ "${shebang} " == *'python3 '* ]]; then
+			from=python3
+		else
 			eerror "A file does not seem to have a supported shebang:"
 			eerror "  file: ${f}"
 			eerror "  shebang: ${shebang}"
 			die "${FUNCNAME}: ${f} does not seem to have a valid shebang"
 		fi
 
-		sed -i -e "1s:python:${impl}:" "${f}" || die
+		if [[ ${from} == python2 && ${impl} == python3*
+				|| ${from} == python3 && ${impl} != python3* ]]; then
+			eerror "A file does have shebang not supporting requested impl:"
+			eerror "  file: ${f}"
+			eerror "  shebang: ${shebang}"
+			eerror "  impl: ${impl}"
+			die "${FUNCNAME}: ${f} does have shebang not supporting ${EPYTHON}"
+		fi
+
+		sed -i -e "1s:${from}:${impl}:" "${f}" || die
 	done
 }
 
-- 
1.8.0.2