Drop non-portable shell option

build.sh

@@ -1,4 +1,4 @@
-#!/bin/sh -Eeuo pipefail
+#!/bin/sh -euo pipefail
 # build.sh -- a bootstrapped image in a migrated Devuan container
 # Copyright (C) 2017  Olaf Meeuwissen
 #

derive.sh

@@ -1,4 +1,4 @@
-#!/bin/sh -Eeuo pipefail
+#!/bin/sh -euo pipefail
 # derive.sh -- handy Devuan images
 # Copyright (C) 2017  Olaf Meeuwissen
 #

migrate.sh

@@ -1,4 +1,4 @@
-#!/bin/sh -Eeuo pipefail
+#!/bin/sh -euo pipefail
 # migrate.sh -- a Debian image to Devuan
 # Copyright (C) 2017  Olaf Meeuwissen
 #