In mysql-server/commit@f46329044f8618212923bdf52e15d5b464201edc
the InnoDB function btr_cur_open_at_rnd_pos() was corrected so that
it would return a status that indicates whether the cursor was
successfully positioned. But this change was not correctly merged to
MariaDB in 2e814d47.

btr_cur_open_at_rnd_pos(): In the code path that was introduced in
MDEV-8588, properly return failure status.

No deterministic test case was found for this failure.
It was caught after removing the function
page_copy_rec_list_end_to_created_page() in a development branch.
As a result, the fill factor of index trees would improve, and
supposedly, so would the probability of btr_cur_open_at_rnd_pos()
reaching the intentionally corrupted page in the test
innodb.leaf_page_corrupted_during_recovery.
The wrong return value would cause
btr_estimate_number_of_different_key_vals() to wrongly invoke
btr_rec_get_externally_stored_len() on a non-leaf page and
trigger an assertion failure at the start of that function.