Revert "redisBufferRead: Clear REDIS_CONNECTED flag when server closed connection"
Revert "redisBufferRead: Clear REDIS_CONNECTED flag when server closed connection"

This reverts commit 1db17f257b1999114c699e77e204f1a91143e5ad.

If the `REDIS_CONNECTED` flag is cleared,
the async onDisconnect callback function will never be called.
This causes problems as the disconnect is never reported back to the user.

Closes #359

owent-contrib/hiredis,owent-contrib/hiredis