Default [Q] Fastboot flash successful, but didn't write

I am trying to flash a Galaxy Nexus back to stock from the image provided by Google.

When I try to flash from fastboot, I get:

sending 'recovery' (4924 KB)...
OKAY [ 0.602s]
writing 'recovery'...
OKAY [ 6.409s]
finished. total time: 7.011s

But the recovery is still CWM, not stock.
The same thing happens with all other partitions: boot, recovery, system, userdata.

fastboot erase also has no effect.

What is wrong?