Linux build dialogs have no font

[VikOlliver]

Under default Ubuntu 18.04 all text in the save file dialogs displays as little boxes, indicating that the desired font has not been found or has been found but is not correctly referenced.

I think the font it's looking for can be found. I used "export FC_DEBUG=8191" to see what is being looked for and got:

fontversion: 155320(i)(s)
capability: "otlayout:DFLT otlayout:arab otlayout:armn otlayout:brai otlayout:cans otlayout:cher otlayout:cyrl otlayout:geor otlayout:grek otlayout:hani otlayout:hebr otlayout:kana otlayout:lao  otlayout:latn otlayout:math otlayout:nko  otlayout:ogam otlayout:runr otlayout:tfng otlayout:thai"(w)
fontformat: "TrueType"(w)
embeddedbitmap: True(s)
decorative: False(s)
lcdfilter: 1(i)(w)
namelang: "en"(s)
prgname: "PancakePainter"(s)
postscriptname: "DejaVuSans-Bold"(w)
color: False(w)
symbol: False(s)
pangoversion: 14014(i)(s)

It's definitely there!
fc-match "DejaVuSans-Bold"
DejaVuSans.ttf: "DejaVu Sans" "Book"

[VikOlliver]

Unfortunately GitHub "Something went really wrong" errors when I try to drag in a screenshot with:

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://github-production-user-asset-6210df.s3.amazonaws.com/. (Reason: CORS request did not succeed).