jQuery 1.5: button() fails when id of input contains dots or square brackets

jQuery 1.5: button() fails when id of input contains dots or square brackets

See fiddle


The error generated is 

Uncaught Syntax error, unrecognized expression: [for=actualResponses[0].answer1]

Which suggests the selector being generated to select the label should be

[for="actualResponses[0].answer1"]

If the id is changed to remove the dots and square brackets it works fine, see