I would check the datasheet for descriptions of internal pull up resistors in the avr chip. see if those are identical on uno and Leonardo chips.
From the product description page:
It is not possible to access the I/O pins of the Atheros AR9331. All I/O lines are tied to the 32U4.
Each of the 20 digital i/o pins on the Yún can be used as an input or output, using pinMode(), digitalWrite(), and digitalRead() functions. They operate at 5 volts. Each pin can provide or receive a maximum of 40 mA and has an internal pull-up resistor**(disconnected by default)** of 20-50 kOhms.