Possibly. The author at least knew enough to observe "Both join fields are indexed. However, MariaDB implements the join with a full scan of project_commits and an index lookup on commits."
That may have actually been a result of the ordering and poor query design.
Given that commits.id is a primary key, IIRC, it must also be NOT NULL; thus the LEFT JOIN is uselessly equivalent to an inner join; which most database engines seem to prefer expressed as a WHERE clause (since it's more trivial to re-order those operations).
Were it an 'inner join' equivalent where clause or the smaller table specified first, at least the full-table scan should have been on the smaller table.
Your database storage engine of choice might differ or have other options (E.G. in PostgreSQL an index on the result of comparing the two source keys COULD be created and a carefully structured query written to use /that/... I think, I haven't tested it but it'd at least be worth the experiment.)
