CREATE TABLE t (a INT) ENGINE=MyISAM;

CREATE TABLE tm (a INT) ENGINE=MERGE UNION(t);

CREATE OR REPLACE TABLE t LIKE tm;

# Cleanup

DROP TABLE IF EXISTS tm, t;

query 'CREATE OR REPLACE TABLE t LIKE tm' failed: 1093: Table 'tm' is specified twice, both as a target for 'CREATE' and as a separate source for data

I'm not sure it should fail at all, since it's LIKE, not CREATE .. SELECT; but even if it should, still the message is wrong – tm is not a target for CREATE, and it is not a source for data since there is no data involved (and a merge table doesn't contain any anyway). It would make more sense if the message was referring t table, at least it is indeed a target for CREATE, and with some stretch it could be claimed that t as an underlying table is a part of tm definition and thus a source for "data".

Note that before MDEV-29697 fix the above fails on a debug build with an assertion failure.