GuestOS is missing on vm which was shut down

Describe the bug

We have some VMs, which are in shut-down state some times. On these VMs no guestOS Informations was given by this pyvmomi tool. I had taken the credentials and SOAP requests from the SoapAdapter.py and pasted it into Postman to check, if there is an issue with pyvmomi or the vSphere API itself. If i send the SOAP requests directly to the vSphere API, i receive the GuetOS information in the response (tested it with the same VM which which was shut down). The pyvmomi response doesn't contain the guestOS information - it is empty.

I don't can find anything else instead of the shut-down-state, what could make an issue there.

I am not sure, if this is a wanted case, that a shut down vm doesn't can contain a vm.

Reproduction steps

1. shut down a vm
2. try to get the guestOS information via pyvmomi tool of the vm in shut-down-state
3. try to make a manual SOAP request to the same vm via another tool (like Postman or SOAP-UI)

Expected behavior

The guestOS information should be also available with shut down vm's.

Additional context

I tried the pyvmomi versions 7.0, 7.0.3 and 8.0.0.1.2 - same issue on each version.

Start by reproducing the report with a shut-down VM, then compare the pyvmomi response with the direct SOAP response described in the issue. Done means pyvmomi exposes the guestOS information for shut-down VMs, with the behavior verified across the reported versions.