Dead lock when importing terms.

Patch attached.

The issue reported in this ticket appears to be the cause of the failing \Drupal\Tests\structure_sync\FunctionalJavascript\StructureSyncMenuLinksTest::testMenuLinksExportImportUsingAdmin() in the 2.x branch.

This patch doesn't apply anymore, possibly because of my work fixing phpcs and phpstan lints while getting GitLab CI → working... sorry about that.

There appears to be a smaller patch in 🐛 Taxonomy imports with relationships may hang Needs work , although it's not passing tests. Let's collaborate there!