Ungoogled Chromium: re-fetches PDFs when saving

If you open a PDF document in the browser (thus in pdf.js) and click the down arrow (↓) to save it locally, it redownloads the document instead of simply saving it from the cache. If you lose network connectivity or disconnect then try to save the PDF locally for later viewing, the browser reports connection issues when there was no need for the network.

Tor Browser (Firefox based) does not have this problem.