$ cp Desktop/h-bridge_sch_pcb.pdf /tmp/h-bridge\ sch\ pcb.pdf

$ /usr/bin/xpdf /tmp/h-bridge\ sch\ pcb.pdf
Error: Couldn't open file '/tmp/h-bridge sch pcb.pdf'

Just in case there's been a recent fix, I did an apt-get install, but
there's no improvement in the behaviour of the package.