searching for a prefix glob should error

Currently searching an index for "*a" does an exact match:

$ ./u1db-client get-from-index /tmp/db1 index '*a' '*'
[{
    "content": {
        "key2": "value2-b",
        "key1": "*a"
    },
    "rev": "c3055cd9fa804dbb9cdb8e91a6e8e47e:1",
    "id": "D-a7dfb97640784d35bad835787939ea76"
}]

it should probably error out, instead.