mroonga files are not copied by mariabackup

Backing up with mariabackup a datadir containing ENGINE=Mroonga tables leaves behind the corresponding *.mrn* files. Those tables are therefore broken once such backup is restored.

I could resolve this issue with the attached one-liner as of 10.3.29. Sadly this does not apply on 11.6 due to this commit:
https://github.com/MariaDB/server/commit/9f98a2acd71dcfbdb32a08e72a4737359ed9be40

Unfortnately, mroonga files do not follow the prefix-match pattern, but instead an infix match. I see the following file names being used (# meaning a hex digit, ${database} being the name of the database the table is in):

• ${database}.mrn
• ${database}.mrn.#######
• ${database}.mrn.#######.###
• ${database}.mrn.#######.c
• ${database}.mrn.#######.c.###

Therefor, the only obvious match seems to be ".mrn is somewhere in the file name". This was easy to introduce in the 10.3 code, but not so easy as of 11.6.

Note on "affected version/s": I selected the version on which I triggered the issue. Grepping in 11.6, the necessary code does not seem to be present.

mroonga/groonga version information:

MariaDB> select @@mroonga_version, @@mroonga_libgroonga_version\G

*************************** 1. row ***************************

           @@mroonga_version: 11.02

@@mroonga_libgroonga_version: 11.0.2