Does reindexdb --concurrently skip over indexes for exclusion constraints, or reindex them separately without the concurrently option? The docs for reindexdb simply point one to the reindex docs for the caveats of concurrently, where that restriction is mentioned.
The REINDEX page says:
"Furthermore, indexes for exclusion constraints cannot be reindexed concurrently. If such an index is named directly in this command, an error is raised. If a table or database with exclusion constraint indexes is reindexed concurrently, those indexes will be skipped. (It is possible to reindex such indexes without the CONCURRENTLY option.)"