I just found out quite by accident that
make clean latexpdf shows a bunch of warnings about missing images that
make clean html does not. (We never build pdfs; I was just trying to do it as a special internal request.) As a result, there are now a bunch of ugly missing images in my live docs, e.g.
https://docs.signalfx.com/en/latest/integrations/integrations-reference/integrations.amazon.redshift.html
Here is a sample warning I see for latexpdf that I don't see for html.
I am going to report this to sphinx, but in the meantime, is there a way to set more verbose warning output for html builds?