Once a AppenderSkeleton called close(),it can't be opened any more.

In ```AppenderSkeleton::closeInternal()```, set ```mIsClosed``` to true, and set ```mIsActive``` to false.
But in ```AppenderSkeleton::activateOptions()```, it only set ```mIsActive``` to true.
Is there have some special reason? 
I want to close a FileAppender, at sometime reactivate it, the ```mIsClosed``` block my way.