Fix --network-interface in systemd-nspawn

Do not fail when modifying an existing link.

Closes: #813696

debian/changelog

@@ -16,6 +16,8 @@ systemd (215-17+deb8u4) UNRELEASED; urgency=medium
   * Only skip the filesystem check for /usr if the /run/initramfs/fsck-usr
     flag file exists. Otherwise we break booting with dracut which uses
     systemd inside the initramfs. (Closes: #810748)
+  * Fix --network-interface in systemd-nspawn to not fail when modifying an
+    existing link. (Closes: #813696)
 
  -- Martin Pitt <mpitt@debian.org>  Sat, 09 Jan 2016 16:24:05 +0100
 

debian/patches/nspawn-fix-network-interface.patch

+From: Tom Gundersen <teg@jklm.no>
+Date: Thu, 28 Aug 2014 12:15:51 +0200
+Subject: nspawn: fix --network-interface
+
+Use SETLINK when modifying an existing link.
+---
+ src/nspawn/nspawn.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
+index c13e625..85191ce 100644
+--- a/src/nspawn/nspawn.c
++++ b/src/nspawn/nspawn.c
+@@ -1760,7 +1760,7 @@ static int move_network_interfaces(pid_t pid) {
+                 if (ifi < 0)
+                         return ifi;
+ 
+-                r = sd_rtnl_message_new_link(rtnl, &m, RTM_NEWLINK, ifi);
++                r = sd_rtnl_message_new_link(rtnl, &m, RTM_SETLINK, ifi);
+                 if (r < 0) {
+                         log_error("Failed to allocate netlink message: %s", strerror(-r));
+                         return r;

debian/patches/series

@@ -157,6 +157,7 @@ core-only-set-the-kernel-s-timezone-when-the-RTC-runs-in-.patch
 delta-Fix-broken-separator-support.patch
 sd-dhcp-client-make-request-broadcasts-configurable.patch
 make-sure-all-swap-units-are-ordered-before-the-swap-targ.patch
+nspawn-fix-network-interface.patch
 
 ## Debian specific patches:
 Add-back-support-for-Debian-specific-config-files.patch