Prior to this commit, the existing script did not work:
swh=> rollback; begin; update revision set extra_headers = ARRAY[][] where extra_headers is null; ROLLBACK BEGIN ERROR: syntax error at or near "[" LINE 1: update revision set extra_headers = ARRAY[][] where extra_he...
With the following diff's content, on staging:
swh=> rollback; begin; update revision set extra_headers = ARRAY[]::bytea[][] where extra_headers is null;
ROLLBACK
BEGIN
UPDATE 865732
swh=> select extra_headers from revision where extra_headers = ARRAY[]::bytea[][] limit 10;
extra_headers
---------------
{}
...I guess it's kinda related to T2524 ;)