Update(Close) UnitSubFlag is useless

[lushilin]

update topic UnitSubFlag has bug, if close unitSubFlag is not useful.

when close unitSubFlag, do not have else logic to close it.

[lizhanhui]

+1 to clean the dead code.

[HScarb]

I think it is a bug.
Although this method is never used, a PR can be submit to fix it, in case someone use it in the future.

[lushilin]

Yes, i think so.
How about this @lizhanhui

[lushilin]

@panzhi33