qemu: managedsave: Check that VM is alive after entering async job

Saving a shutoff VM doesn't make sense and libvirtd crashes while
attempting to do that. Check that the domain is alive after entering
the save async job.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1129207

src/qemu/qemu_driver.c

@@ -3096,6 +3096,12 @@ qemuDomainSaveInternal(virQEMUDriverPtr driver, virDomainPtr dom,
     if (qemuDomainObjBeginAsyncJob(driver, vm, QEMU_ASYNC_JOB_SAVE) < 0)
         goto cleanup;
 
+    if (!virDomainObjIsActive(vm)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("guest unexpectedly quit"));
+        goto endjob;
+    }
+
     memset(&priv->job.info, 0, sizeof(priv->job.info));
     priv->job.info.type = VIR_DOMAIN_JOB_UNBOUNDED;