Do not run those commands with MariaDB GTIDs - part # 1

In the spirit of sharing war stories and avoiding others to do the same mistakes as I did, here are some sequences of commands that you should avoid to run on a MariaDB slave that is lagging and which is using the GTID protocol.  Remember, do not run those because...

So, those bad commands are the following:

• "STOP SLAVE; START SLAVE UNTIL ...;",
• or "STOP SLAVE; START SLAVE;" (to remove an UNTIL condition as an example),
• or "STOP SLAVE; SET GLOBAL slave_parallel_threads=...; START SLAVE;",
• and maybe others.

Can you guess why those commands are bad (or other sequence of commands that would be bad in the same way) ?  If yes, post a comment.  I will give more details in part # 2, including better options.

Update: part #2 has been published.

Note: MySQL also has similar problems, I have just not been bitten by them recently, more in part # 2.