Add space:truncate() to the end of box.net.box test

test/box/net.box.result

@@ -179,3 +179,6 @@ lua remote:ping()
 ---
 error: '[string "box.net = {..."]:407: box.net.box: connection was closed'
 ...
+lua box.space[0]:truncate()
+---
+...

test/box/net.box.test

@@ -61,3 +61,6 @@ exec admin "lua box.time() - pstart < 0.5"
 exec admin "lua remote:close()"
 exec admin "lua remote:close()"
 exec admin "lua remote:ping()"
+
+exec admin "lua box.space[0]:truncate()"
+