redis-cli: always report server errors on read errors.
redis-cli: always report server errors on read errors.

Before this commit we may have not consumer buffers when a read error is
encountered. Such buffers may contain errors that are important clues
for the user: for instance a protocol error in the payload we send in
pipe mode will cause the server to abort the connection. If the user
does not get the protocol error, debugging what is happening can be a
nightmare.

This commit fixes issue #3756.

JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis