Deleting quad does not work as expected

[sofiashalotenko]

Description

Say you create a quad "a,b,c,d". As expected g.V().All() gives {"result":[{"id":"a"},{"id":"b"},{"id":"c"},{"id":"d"}]} and g.V().Out().All() gives {"result":[{"id":"c"}]}.

BUT when you delete quad "a,b,c,d", g.V().Out().All() gives null (as expected) but g.V().All() STILL gives {"result":[{"id":"a"},{"id":"b"},{"id":"c"},{"id":"d"}]}.

Steps to reproduce the issue:

1. Using the backend of sql or leveldb, create a quad "a,b,c,d"
2. Delete quad "a,b,c,d"
3. Do query "g.V().All()"

Received results:

"result":[{"id":"a"},{"id":"b"},{"id":"c"},{"id":"d"}]}

Expected results:

{
 "result": null
}

Output of cayley version or commit hash:

Cayley v0.6.1

Environment details:

Backend database: (sql or leveldb)