Check abort only if percentage changed

This avoids checking abort too frequently.

disk.py

@@ -278,9 +278,9 @@ class Disk(object):
                     f.write(chunk)
                     current_size = f.tell()
                     new_percent = current_size * 100 / clen
-                    if task.is_aborted():
-                        raise AbortException()
                     if new_percent > percent:
+                        if task.is_aborted():
+                            raise AbortException()
                         percent = new_percent
                         task.update_state(
                             task_id=parent_id,
@@ -337,9 +337,9 @@ class Disk(object):
 
         def update_state(monitor):
             new_percent = monitor.bytes_read * 100 / size
-            if task.is_aborted():
-                raise AbortException()
             if new_percent > percent[0]:
+                if task.is_aborted():
+                    raise AbortException()
                 percent[0] = new_percent
                 task.update_state(
                     task_id=parent_id,