core: Revert using the unified hierarchy for the systemd cgroup

Too many things don't get along with it yet, like docker, LXC, or runc.

Forwarded to systemd/systemd#4628.

Closes: #843509

debian/patches/debian/core-don-t-use-the-unified-hierarchy-for-the-systemd-cgro.patch

@@ -0,0 +1,34 @@
+From: Martin Pitt <martin.pitt@ubuntu.com>
+Date: Wed, 9 Nov 2016 08:43:57 +0100
+Subject: core: don't use the unified hierarchy for the systemd cgroup yet
+
+Too many things don't get along with the unified hierarchy yet:
+
+ * https://github.com/opencontainers/runc/issues/1175
+ * https://github.com/docker/docker/issues/28109
+ * https://github.com/lxc/lxc/issues/1280
+
+So revert the default to the legacy hierarchy for now. Developers of the above
+software can opt into the unified hierarchy with
+"systemd.legacy_systemd_cgroup_controller=0".
+---
+ src/basic/cgroup-util.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
+index 735f204..76c6d61 100644
+--- a/src/basic/cgroup-util.c
++++ b/src/basic/cgroup-util.c
+@@ -2421,10 +2421,10 @@ bool cg_is_unified_systemd_controller_wanted(void) {
+
+                 r = get_proc_cmdline_key("systemd.legacy_systemd_cgroup_controller=", &value);
+                 if (r < 0)
+-                        return true;
++                        return false;
+
+                 if (r == 0)
+-                        wanted = true;
++                        wanted = false;
+                 else
+                         wanted = parse_boolean(value) <= 0;
+         }

debian/patches/series

@@ -25,3 +25,4 @@ debian/Revert-core-set-RLIMIT_CORE-to-unlimited-by-default.patch
 debian/Revert-core-enable-TasksMax-for-all-services-by-default-a.patch
 debian/Let-graphical-session-pre.target-be-manually-started.patch
 debian/Drop-RestrictAddressFamilies-from-service-files.patch
+debian/core-don-t-use-the-unified-hierarchy-for-the-systemd-cgro.patch