pt-stalk with --system-only displaying "MYSQL_ONLY:" message on the screen

The "--system-only" option is a great feature for using pt-stalk with PostgreSQL and MongoDB. A message like "MYSQL_ONLY:" confuses the end-user when collecting data for PostgreSQL.

./pt-stalk --system-only --no-stalk --iterations=4 --sleep=30

output

2022_10_28_03_41_38 Not stalking; collect triggered immediately
2022_10_28_03_41_38 Collect 1 triggered
2022_10_28_03_41_38 MYSQL_ONLY: 
...

It will be great if 

pt-stalk --system-only

is completely database-neutral from the user experience perspective.

Best Regards,

Jobin.