No WIFI when running Wireless Beaglebone Black on Battery

Wifi is not powered up when running off of a 3.7v Lithium Ion battery. Schematic shows a series diode (D2) to source SYS_5v to the wifi regulator. This diode is missing on my Wireless Beaglebone black.

Is there some reason why this part has been omitted?

I also have an older Beaglebone Black (Ver A6a) with the wifi cape modified to be powered off of the SYS_5V. The wifi-cape look to be basically the same circuit as on the wireless Beaglebone Black. I have not seen any problems with wifi running off of the lithium-ion battery.

Thanks for any assistance,