LP #1566939: pt-stalk should not call mysqladmin debug by default

**Reported in Launchpad by Valerii Kravchuk last update 06-04-2016 16:17:22

mysqladmin debug output is NOT properly documented and is of limited use as a result (see https://bugs.mysql.com/bug.php?id=71346). On the other hand, we see that this call is used almost unconditionally in pt-stalk:

[[email protected] git]$ grep -rn MYSQLADMIN `which pt-stalk`
780:CMD_MYSQLADMIN="${CMD_MYSQLADMIN:-"$(_which mysqladmin)"}"
830: $CMD_MYSQLADMIN $EXT_ARGV debug
894: $CMD_MYSQLADMIN $EXT_ARGV ext -i$OPT_SLEEP_COLLECT -c$cnt >>"$d/$p-mysqladmin" &
1011: local open_tables=$($CMD_MYSQLADMIN $EXT_ARGV ext | grep "Open_tables" | awk '

')
2132:=item CMD_MYSQLADMIN
[[email protected] git]$

...
824 local tail_error_log_pid=""
825 if [ "$mysql_error_log" ]; then
826 log "The MySQL error log seems to be $mysql_error_log"
827 tail -f "$mysql_error_log" >"$d/$p-log_error" &
828 tail_error_log_pid=$!
829
830 $CMD_MYSQLADMIN $EXT_ARGV debug
831 else
832 log "Could not find the MySQL error log"
833 fi
834
835 if [ "${mysql_version}" '>' "5.1" ]; then
836 local mutex="SHOW ENGINE INNODB MUTEX"
837 else
838 local mutex="SHOW MUTEX STATUS"
839 fi
840 innodb_status 1
841 tokudb_status 1
...

The outputs of this command pollute error log and force users to ask why is it there when they had NOt explicitly asked for it, wonder is it an indication of a problem etc (imagine pt-stalk working as a daemon and collect9ing statistics periodically).

So, I suggest to disable this call by default and let user enable it if needed with a separate option.