libpciaccess bogus bridge data - commit 2bda5b73

[Bryce Harrington]

Jesse,

I have a question about change 2bda5b73 that you did to libpciaccess
last year, to stop pci_device_get_bridge_buses() from looking at bus
data if the bridge data was not read.

A ubuntu bug reporter says that this check is preventing his device from
getting detected properly - see

 https://bugs.launchpad.net/ubuntu/+source/libpciaccess/+bug/681207

Looking at the code I see that for case 0x04 there's already a check for
NULL, where it attempts to re-read the bridge info, so presumably there
are at least some situations where NULL bridge.pci is expected?

What I'm wondering is if the check should be less strict in cases of
multi-function cards, or if somewhere else in the code needs updated to
read these devices properly.

Bryce