forum gives no specific error message

Problem & Analysis: 
===================
When a new slave joins to a replication forum with uuid which
is exactly same as one of the existing slave's uuid, then master is 
confused between old slave and the newly joined slave. When com_binlog_send
request comes from newly joined slave, it thinks that old slave's dump
thread is zombie and kills it. After some time, old slave tries to reconnect
to the master and sends com_binlog_send request to Master. Then Master
thinks that newly joined slave's dump thread is zombie and kills it.
This ping-pong reconnections between Master->old_slave and Master->new_slave
happens continously. This is known expected behaviour but the
error message in old_slave and new_slave's error log file is not clear
enough to identify this situation.

Information in error log file was:
"received end packet from server, apparent master shutdown" which
does not say anything about server_uuid misconfiguration in the
replication forum.

Fix: Changing the error message which clearly mentions all the possible
causes which resulted this disconnection.

New information in error log file is: 
"Slave: received end packet from server due to dump thread being killed on master.
Dump threads are killed for example during master shutdown,
explicitly by a user, or when the master receives a binlog send
request from a duplicate server UUID <server_uuid>. "

And also a NOTE is added on master's error log file with the following
information when log_warnings is greater than 1.
"While initializing dump thread for slave with UUID <slave_uuid>,
found a zombie dump thread with the same UUID.
Master is killing the zombie dump thread."