I2C on ESP8266 broken in 1v92 and later, worked in 1v91

Something is seriously busted relating to I2C in recent version of Espruino for ESP8266. 1v91 works, 1v92 and later does not...
Connect and AT24 EEPROM chip - the simplest I2C device you can get. It can read just fine on 92 and later, but write doesn't work for some strange reason!

I2C1.setup({scl:5,sda:4});
var eeprom=require("AT24").connect(I2C1, 64, 256);

On 1v92:

>eeprom.read(0,10);
=new Uint8Array([70, 117, 99, 107, 32, 116, 104, 101, 32, 112])
>eeprom.write(0,[123,212])
=2
>eeprom.read(0,10);
=new Uint8Array([70, 117, 99, 107, 32, 116, 104, 101, 32, 112])

On 1v91:

>eeprom.read(0,10)
=new Uint8Array([70, 117, 99, 107, 32, 116, 104, 101, 32, 112])
>eeprom.write(0,[123,212])
=2
>eeprom.read(0,10)
=new Uint8Array([123, 212, 99, 107, 32, 116, 104, 101, 32, 112])

No hardware changes between the two test cases - exact same ESP8266 board. I just flashed different espruino versions on it between these two tests.

Is there a workaround for this? Has anyone else noticed this?!