virt._get_domain: don't raise an exception if there is no VM

[cbosdo]

What does this PR do?

Raising an exception if there is no VM in virt._get_domain makes sense if
looking for some VMs, but not when listing all VMs.

What issues does this PR fix or reference?

Previous Behavior

Running this on a hypervisor minion without any VM raises an exception:

salt 'kvm' virt.list_domains

New Behavior

Running the same command without any VM only returns an empty list

Tests written?

Yes

Commits signed with GPG?

Yes

Please review Salt's Contributing Guide for best practices.

See GitHub's page on GPG signing for more information about signing commits with GPG.

[brejoc]

👍

[brejoc]

@saltstack/team-core Would be cool if we might get a go nor no-go here from you. Then we could still squeeze this into the next SLE release. Thanks and sorry for pushing!

[cbosdo]

just rebased on top of master

[cbosdo]

rebased on master

[DmitryKuzmenko]

Thank you for PR! It's perfect. Lets wait for tests.

[DmitryKuzmenko]

@cbosdo could you please resolve merge conflicts?

[cbosdo]

@DmitryKuzmenko rebased

[DmitryKuzmenko]

I've slightly updated the test (isort and "/' in check string). Now it should be ready. Lets wait for tests.

[cbosdo]

@DmitryKuzmenko I've seen that isort and black are sometimes doing conflicting changes... which to believe then?

[DmitryKuzmenko]

@cbosdo this is a good point but I haven't seen such behavior. Do you have an example?

[cbosdo]

@cbosdo this is a good point but I haven't seen such behavior. Do you have an example?

As an example in PR #55814, running isort salt/states/virt.py will create this diff:

--- a/salt/states/virt.py
+++ b/salt/states/virt.py
@@ -25,7 +25,6 @@ import salt.utils.files
 import salt.utils.stringutils
 import salt.utils.versions
 from salt.exceptions import CommandExecutionError
-
 # Import 3rd-party libs
 from salt.ext import six
 

Applying black on that same file again, removes the change.

[DmitryKuzmenko]

@cbosdo Hah! Really works if run isort and black manually but pre-commit hook doesn't do any change on that file.

[cbosdo]

yeah it depends on the run order of isort and black

[waynew]

Less the run order, and more the version. When isort 5 is released it will contain the black friendly option to put spaces before comments.

[waynew]

If you run pre-commit run isort you shouldn't see this diff

[cbosdo]

OK, will try for my next commits :)