fs-routing-clamp: failure of fs_routing_test at open() calls

[drapl0n]

Running grate test suite results in failure of fs-routing-clamp grate test caused by open() syscalls:

lind-wasm grates/fs-routing-clamp.cwasm --prefix /tmp %{ grates/testing-grate.cwasm -s 0:166,1:166,2:166,4:166,21:166,83:166,84:166,87:166 %} fs_routing_test.cwasm

FAIL: open /tmp/ns_test_file routed to clamp (errno=0)
FAIL: open /tmp/ns_test routed to clamp (errno=0)
FAIL: open /tmp/ns_interleave_0 routed to clamp (errno=9)
FAIL: open /tmp/ns_interleave_2 routed to clamp (errno=9)
FAIL: open /tmp/ns_interleave_4 routed to clamp (errno=9)
FAIL: open deep /tmp path routed to clamp (errno=9)