processlist on slave":
we now report in SHOW PROCESSLIST that we are writing to the temp
files or loading the table. When we are writing to the tmp file:
| 3  | system user |                 |    | Connect | 6    | Making temp file /tmp/SQL_LOAD-2-1-2.data | 
and when we are actually loading the .data temp file into the table:
| 3  | system user |                 | test | Connect | 2    | | LOAD DATA INFILE '/tmp/SQL_LOAD-2-1-2.data' INTO TABLE `t` <...> |


sql/log_event.cc:
  Replication of LOAD DATA INFILE:
  we now report in SHOW PROCESSLIST that we are creating
  the temp files or loading the table.
  Plus removing a line which had a comment "should not be needed"
  and a guarding assertion which we have never heard fail (and logic
  says it should not fail).