pm-utils installs /usr/lib/pm-utils/power.d/wireless which is among those scripts executed whenever a laptop switches to battery.
This script checks for /sys/class/net/*/wireless/ to determine whether it sees a wireless interface.
The existence of this depends on CONFIG_WIRELESS_EXT_SYSFS. Linux menuconfig warns that this is going to be removed soon and that userspace should be updated.
Upstream bug (also contains a patch):
sorry, correct link here:
The problem with the patch from upstream bug is that this would add extra dependency, to 'wireless-utils', which is also deprecated, in favour of 'iw'
Not sure what to do here :-(