Bug#27070 server logs are created unrequested and in wrong directory

 - Avoid defaault log file names looking like <hostname>.pid.slow.log
  by using the FN_REPLACE_EXT flag to 'fn_format'
 - Remove the default log files generated by log_state.test before
   test completes

mysql-test/t/log_state.test

@@ -132,3 +132,8 @@ select * from mysql.general_log;
 # Cleanup (must be done last to avoid delayed 'Quit' message in general log)
 #
 disconnect con1;
+
+# Remove the log files that was created in the "default location"
+# i.e var/run
+--remove_file $MYSQLTEST_VARDIR/run/master.log
+--remove_file $MYSQLTEST_VARDIR/run/master-slow.log

sql/log.cc

@@ -68,7 +68,7 @@ char *make_default_log_name(char *buff,const char* log_ext)
 {
   strmake(buff, pidfile_name, FN_REFLEN-5);
   return fn_format(buff, buff, mysql_data_home, log_ext,
-                   MYF(MY_UNPACK_FILENAME|MY_APPEND_EXT));
+                   MYF(MY_UNPACK_FILENAME|MY_REPLACE_EXT));
 }
 
 /*