cgfsng: fix lxc.pivot directory creation

src/lxc/cgroups/cgfsng.c

@@ -1152,6 +1152,7 @@ __cgfsng_ops static void cgfsng_monitor_destroy(struct cgroup_ops *ops,
 
 	for (int i = 0; ops->hierarchies[i]; i++) {
 		int ret;
+		char *chop;
 		struct hierarchy *h = ops->hierarchies[i];
 
 		if (!h->monitor_full_path)
@@ -1169,10 +1170,17 @@ __cgfsng_ops static void cgfsng_monitor_destroy(struct cgroup_ops *ops,
 						    PIVOT_CGROUP,
 						    "cgroup.procs", NULL);
 
+		chop = strrchr(pivot_path, '/');
+		if (chop)
+			*chop = '\0';
+
 		ret = mkdir_p(pivot_path, 0755);
 		if (ret < 0 && errno != EEXIST)
 			goto next;
 
+		if (chop)
+			*chop = '/';
+
 		/* Move ourselves into the pivot cgroup to delete our own
 		 * cgroup.
 		 */