Inconsistent MusicBrainz import due to parallelism
After changes for five tests fail.
As part of a refactoring, the sorting has been inserted. The test set
has been updated to version 20210408_2135.
Much likely is a race condition that didn’t trigger before. The five records are substantially equal, so the rules for picking a primary one fail; and the fallback rule is to pick the one with the first MusicBrainz UUID in lexicographic order. But a FIXME in the code points out that there is no sorting.
The tests are related to MusicBrainz multiple entries for five records. The importer has some rules to decide what is considered the “main” entry, while others are labeled as ‘alternatePickOf’. The choice is different now, hence the failed tests.