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Last tested: Jan 14, 2019
There's no way to do this from Looker right now. You can potentially see it on your DB, or by selecting the Show Processes option in SQL Runner's cog menu next to the connection which should show rebuilds both in dev and prod.
In order to identify dev mode PDT builds (i.e. which user kicked off a rebuild), you can look at the comments in the statement which was sent to the db. If you can access the db logs, that would have a user id.