Fix CI environment variable passing; write CI vars to /etc/environment

Makefile

@@ -16,7 +16,6 @@ qemu_disk = tmp/qemu-disk.img
 qemu_target ?= debian-stretch
 qemu_kernel = $(qemu_target).linux
 qemu_torrent = $(qemu_target).torrent
-
 qemu_initramfs = $(shell \
 if [ -e $(qemu_target).initramfs.dev ] && [ `date -r $(qemu_target).initramfs.dev +%s` -gt `date -r $(qemu_target).initramfs +%s` ]; then \
 	echo "$(qemu_target).initramfs.dev"; \
@@ -24,6 +23,7 @@ else \
 	echo "$(qemu_target).initramfs"; \
 fi \
 )
+ci_environment=$(shell env | sed -n 's/^\(CI_.*\)=.*/-e \1/p')
 
 .PHONY: default
 default: dockerimg images/debian-stretch.squashfs
@@ -51,6 +51,7 @@ images/debian-stretch.squashfs: images
 		-e "group=`id -g`" \
 		-e "ANNOUNCE=$(ANNOUNCE)" \
 		-e "WEBSEED=$(WEBSEED)" \
+		$(ci_environment) \
 		"$(DOCKER_IMAGE)" \
 		debian-stretch