bug(add_book): walrus operator in author dedup loop assigns bool instead of key string

[mekarpeles]

Problem

In catalog/add_book/load_book.py, an author deduplication loop uses a walrus operator with incorrect operator precedence. The dedup never works for any record with more than one author.

Location

openlibrary/catalog/add_book/load_book.py — in import_record_to_edition().

Bug

# Current (buggy):
seen = set()
for a in authors:
    if key := a["key"] in seen:  # walrus: key = (a["key"] in seen) — bool, not string
        continue
    seen.add(key)  # adds False or True, not the author key string

The walrus operator := has lower precedence than in. Python parses this as key := (a["key"] in seen). So:

• key is assigned the boolean result of a["key"] in seen
• After the first iteration: seen = {False}
• For all subsequent iterations: a["key"] in seen is False (a key string is not in {False}), so seen.add(False) is a no-op

The intended deduplication never triggers for records with 2+ authors.

Fix

seen = set()
for a in authors:
    if a["key"] in seen:
        continue
    seen.add(a["key"])

Impact

The runtime impact is benign in most cases — downstream author-resolution logic handles actual deduplication at a different level. However, the broken loop means:

• Every record with multiple authors does redundant work
• If two authors in the same record have identical OL keys, both are passed downstream instead of one being deduplicated

Related

This is a pure author deduplication bug within import_record_to_edition(), separate from the author-matching logic in match.py.

[addy790]

Hi, I'd like to work on this the fix looks straightforward, will submit a PR shortly.