[PATCH] qemuDomainPostParseDataAlloc: Don't reset error if looking up caps fails

[Peter Krempa]

On Fri, Jul 17, 2020 at 09:27:54 +0200, Michal Privoznik wrote:
> When starting the QEMU driver we load all domain XMLs. This
> means, that post parse callbacks are run for each XML, but they
> are allowed to fail because we will run them again when starting
> a domain. In the case I am fixing, we were unable to look up QEMU
> capabilities (in both post parse runs) and reported appropriate
> error, sort of. It can be found in the logs, but the caller
> doesn't get it because after 5331c4804f4 it is reset. Therefore,
> as reported here [1], if we are unable to start QEMU for caps
> probing the following will happen:
> 
>   virsh start fedora
>   error: Failed to start domain fedora
>   error: An error occurred, but the cause is unknown
> 
> 1: https://www.redhat.com/archives/libvir-list/2020-July/msg00673.html
> 
> Fixes: 5331c4804f4

FYI Daniel already posted his version of the fix which does a bit more:

https://www.redhat.com/archives/libvir-list/2020-July/msg00804.html