SQLite used INSERT INTO tbl SELECT %s UNION SELECT %s, the problem
was that there should have been UNION ALL instead of UNION.
Refs #19351
Backpatch of a27582484cf814554907d2d1ad077852de36963f
The qs.bulk_create() method did not work with large batches together
with SQLite3. This commit adds a way to split the bulk into smaller
batches. The default batch size is unlimited except for SQLite3 where
the batch size is limited to 999 SQL parameters per batch.
Thanks to everybody who participated in the discussions at Trac.
Backpatch of 29132ebdef0e0b9c09e456b05f0e6a22f1106a4f from master (with
documentation changes removed).
