get_already_received_qty (sum over Purchase Receipt Item, parent != self.name)
and the two Purchase-Invoice-against-receipt existence checks (implicit
comma-joins -> child-table get_all on Purchase Invoice Item, docstatus=1).
Also fixes a pre-existing `self.submit_rv` -> `submit_rv` typo in the (dead)
check_next_docstatus that staging carried forward. Same result on MariaDB;
valid under Postgres.
Tests: get_already_received_qty (parent-exclusion sum) and check_next_docstatus
(blocks on a submitted Purchase Invoice; also locks the typo fix).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
a65aa27225