CREATE TEMPORARY TABLE from MERGE and read-only access

[Nick Kostirya]

Нello All.

We use one and the same database (MyISAM and MERGE tables), files of which
have reado-only access at the file ststem level (OS is Linux).
Everything worked perfectly until we used MySQL versions up to 4.1.20.
And having switched to MySQL version 4.1.22 we have found out that
when a TEMPORARY TABLE is created on the basis of a MERGE table,
MySQL requires write access to database files. If there are no rights
to write, then the following error appears:

"ERROR 1168 (HY000): Unable to open underlying table which is differently
defined or of non-MyISAM type or doesn't exist".

When creating a TEMPORARY TABLE basing on MyISAM such a thing doesn't
happen, everything works fine.

Thus, here is the question: is this a normal situation or a bug in
version 4.1.22?

 Best regards, Nick.