Starts with attribute selector doesn't work: [attribute^=value]

[cuzzo]

Subject of the issue

I don't appear able to select attributes using the starts with selector: [attribute^="value"]. I'm able to select the elements just fine if I use a much more brittle selector, so it doesn't appear to be an issue with the request.

Your environment

node version: v4.2.6
npm version: 3.5.2

Steps to reproduce

var x = require("x-ray")();
x(
"https://www.goodreads.com/work/shelves/21500681", {
genres: "[href^="/genres"]"
}
)
.limit(1)
.write("genres.json");

Expected behaviour

I would exepct to get a list of all genres on the page, similar to the results of this selector: [".shelfStat a"]

Actual behaviour

I get an empty array.