[Rd] italic font on cairo devices in R 3.4

[Ilia Kats]

[cross-post from R-help]

Hi all,

I have the following problem: Since R 3.4.0, italic fonts rendered on 
Cairo devices appear pixelated. Here's a minimal example:
cairo_pdf('test.pdf')
plot(1:10, ylab=expression(italic(test)))
dev.off()

The same problem occurs with bolditalic, but not bold. I am using Debian 
Stretch. Several friends tried the same on their machines, another 
Debian machine has the same problem. On MacOSX the output was not 
pixelated, but it wasn't italic either. Ubuntu 16.04.2 xenial works 
fine. My impression is that R somehow can't find the proper font to use 
and falls back to something weird. Ideas?

Note that I'm not subscribed to the list, so please CC me in replies.

Cheers, Ilia