Hi dottedquad,
Sorry for the delay. As I explained, the Edison GPIO has a programmable internal pullup resistor which value could be 2, 20, or 50 kOhm, and for those pins used for I2C there is an extra value of 910 Ohm. If you choose for example 2 kOhm as internal pullup resistor, and then you plug the 4.7 kOhm external pullup resistor, the equivalent pullup resistor would be 1.4 kOhm (the two resistors are in parallel). That is the detail I was referring to.
If you need for example the 4.7 kOhm pullup resistor, my suggestion is to disable the internal pullup resistor and only use the desired external pullup value.
Regards,
Diego.