Cannot launch qabro on a platform without pci

[Patrick Liu]

I was trying to use qabro on my arm64 uc20 project. Our project does not have a PCI bus in design.
When launching qabro with the following command, it raises an error.

patliu@Ambarella:~$ snap install qabro --devmode
qabro 0.14 from Pierre Equoy (pieq) installed
patliu@Ambarella:~$ qabro
pcilib: Cannot open /proc/bus/pci
lspci: Cannot find any working access method.
Traceback (most recent call last):
  File "/snap/qabro/135/bin/qabro", line 33, in <module>
    sys.exit(load_entry_point('qabro==0.14', 'console_scripts', 'qabro')())
  File "/snap/qabro/135/lib/python3.6/site-packages/qabro/__init__.py", line 65, in main
    tags=args.tags)
  File "/snap/qabro/135/lib/python3.6/site-packages/qabro/__init__.py", line 72, in start_ui
    tags=tags.lower())
  File "/snap/qabro/135/lib/python3.6/site-packages/qabro/ui.py", line 49, in __init__
    std_info = AttachmentAssistant.get_standard_info()
  File "/snap/qabro/135/lib/python3.6/site-packages/qabro/bug_assistant.py", line 386, in get_standard_info
    lspci_output = (subprocess.check_output(['lspci', '-nn'])
  File "/snap/qabro/135/usr/lib/python3.6/subprocess.py", line 356, in check_output
    **kwargs).stdout
  File "/snap/qabro/135/usr/lib/python3.6/subprocess.py", line 438, in run
    output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['lspci', '-nn']' returned non-zero exit status 1.

[Failure rate]
100%

[Additional information]
Hardware: ARM 64
Image: uc20 for our project
CPU: 4 core, Cortex A53
RAM: 1GB DDR4
Kernel: 5.4

[Pierre Equoy (pieq)]

According to OP, the device in question does not have a PCI Bus, which results to lspci not being able to run.

Indeed, if trying to run lspci from within the snap, we get the same error:

$ snap run --shell qabro
user@hostname:/home/user$ lspci
pcilib: Cannot open /proc/bus/pci
lspci: Cannot find any working access method.

QAbro has to be made more flexible and not fail if lspci returns an error.