Add new wiki page - error writing to database

Hi,

I couldn't find a relevant 2.3 QA test for this but just came across this.

Error writing to database

Debug info: Duplicate entry '1-0-0' for key 'mdl_wikisubw_wikgrouse_uix'
INSERT INTO mdl_wiki_subwikis (wikiid,groupid,userid) VALUES(?,?,?)
[array (
0 => '1',
1 => '0',
2 => '0',
)]
Error code: dmlwriteexception
Stack trace:
line 416 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 952 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 994 of /lib/dml/mysqli_native_moodle_database.php: call to mysqli_native_moodle_database->insert_record_raw()
line 104 of /mod/wiki/locallib.php: call to mysqli_native_moodle_database->insert_record()
line 950 of /mod/wiki/pagelib.php: call to wiki_add_subwiki()
line 115 of /mod/wiki/create.php: call to page_wiki_create->create_page()

—

Steps to replicate:

1. Add a new wiki activity
2. Default format: HTML; Force format: Select
3. Save a display
4. Add some content to first page and include a word or phrase in [[double square brackets]]
5. Save
6. Select the red italicised text in [[double square brackets]]