This issue seems to be caused by empty glyphs ending up in the 2.36 source package. I reported the bug upstream yesterday. https://bugs.freedesktop.org/show_bug.cgi?id=97081
The DejaVu folks will probably fix this soon enough, but in the meantime you can download working 2.36 files from http://dejavu-fonts.org/wiki/Download and use them. That's what I did.
