lib:: fix copy problem.

cannot copy a file and its copy at the same time.

tower:https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/e4dd4cd051ec4226a4f712e7ebd484c4/
Change-Id: I5b6ab1517d8d4866c990beaf72b17e334ce973b3