live: reworked use/live/repo

The expected behaviour is to have online repositories enabled
when the livecd is running; the trouble with runtime detection
relates to the asynchronous nature of network configuration,
connection might get probed just before it is brought up
(thus failing the test).

Systems having been installed-from-live don't misbehave this way
so left unmolested.

Runtime detection is still available via use/live/repo/online
but is definitely not the default mechanism.

features.in/live/config.mk

@@ -31,9 +31,14 @@ use/live/desktop: use/live/base use/x11/wacom use/live/sound \
 	@$(call add,SYSLINUX_CFG,localboot)
 
 # preconfigure apt for both live and installed-from-live systems
-use/live/repo:
-	@$(call add,LIVE_PACKAGES,livecd-online-repo)
+use/live/repo: use/live
 	@$(call add,LIVE_PACKAGES,installer-feature-online-repo)
+	@$(call try,LIVE_REPO,http/alt)
+	@$(call xport,LIVE_REPO)
+
+# preconfigure apt in runtime (less reliable)
+use/live/repo/online:
+	@$(call add,LIVE_PACKAGES,livecd-online-repo)
 
 # alterator-based permanent installation
 use/live/install: use/metadata use/syslinux/localboot.cfg

features.in/live/live/image-scripts.d/60-apt

@@ -0,0 +1,10 @@
+#!/bin/sh
+# unconditionally enable online repository
+
+[ -n "$GLOBAL_LIVE_REPO" ] || exit 0
+
+PROTO="${GLOBAL_LIVE_REPO%/*}"	# http, ftp, rsync
+MIRROR="${GLOBAL_LIVE_REPO#*/}"	# alt, heanet, kiev, yandex, ...
+
+sed -i "s,^#\(rpm \[alt\] ${PROTO:-http}.*\),\1," \
+	"/etc/apt/sources.list.d/${MIRROR:-alt}.list"

pkg.in/lists/tagged/base+regular

@@ -5,7 +5,6 @@ strace
 powertop
 acpi
 
-livecd-online-repo
 apt-repo
 update-kernel
 synaptic-usermode