no good way to remove a variable from namespace

[shoenig]

E.g. I want to remove CONSUL_HTTP_TOKEN from

[NUC10 consul-tls-connect (master)] $ envy show --decrypt test
CONSUL_CACERT=consul-agent-ca.pem
CONSUL_CLIENT_CERT=dc1-server-consul-0.pem
CONSUL_CLIENT_KEY=dc1-server-consul-0-key.pem
CONSUL_HTTP_ADDR=https://127.0.0.1:8500
CONSUL_HTTP_SSL=true
CONSUL_HTTP_TOKEN=e7de65c5-16b8-5f4d-0570-77cdde93ea64
CONSUL_PORT=8500
CONSUL_SCHEME=https

after disabling ACLs, but I cannot

[NUC10 consul-tls-connect (master)] $ envy update test set CONSUL_HTTP_TOKEN=''
envy: unable to parse args: malformed environment variable pair
[NUC10 consul-tls-connect (master)] $ envy update test set CONSUL_HTTP_TOKEN=" "
envy: unable to parse args: malformed environment variable pair