qemuCheckpointCreateXML: Check VM liveness first

Move the liveness check prior to the capability check. If the VM is
offline the capabilities are not initialized and thus we'd report the
wrong error.

https://bugzilla.redhat.com/show_bug.cgi?id=1812531Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_checkpoint.c

@@ -647,15 +647,15 @@ qemuCheckpointCreateXML(virDomainPtr domain,
         update_current = false;
     }
 
-    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
+    if (!virDomainObjIsActive(vm)) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("incremental backup is not supported yet"));
+                       _("cannot create checkpoint for inactive domain"));
         return NULL;
     }
 
-    if (!virDomainObjIsActive(vm)) {
+    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_INCREMENTAL_BACKUP)) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("cannot create checkpoint for inactive domain"));
+                       _("incremental backup is not supported yet"));
         return NULL;
     }