libnftables: release top level scope

Otherwise bogus variable redefinition are reported via -o/--optimize:

  redefinition.conf:5:8-21: Error: redefinition of symbol 'interface_inet'
  define interface_inet = enp5s0
         ^^^^^^^^^^^^^^

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 15 insertions, 0 deletions

diff --git a/tests/shell/testcases/optimizations/variables b/tests/shell/testcases/optimizations/variables
new file mode 100755
index 00000000..fa986065
--- /dev/null
+++ b/tests/shell/testcases/optimizations/variables
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+set -e
+
+RULESET="define addrv4_vpnnet = 10.1.0.0/16
+
+table ip nat {
+    chain postrouting {
+        type nat hook postrouting priority 0; policy accept;
+
+        ip saddr \$addrv4_vpnnet counter masquerade fully-random comment \"masquerade ipv4\"
+    }
+}"
+
+$NFT -c -o -f - <<< $RULESET