Stalls on MacOS

This bug was originally reported by Gilles Fernandez (gilles.fernandez10@gmail.com) in Debian bug #897346:

diffoscope version: 93
pdftotext version: 3.03
pdftk version: 2.02

I had a few dependencies problems with pdftotext and pdftk (I’m under Mac OS),
but in the end found it and installed it.

But now when I run it on 2 PDFs, I get the program on stall, not doing anything
after a few seconds. top tells me there is no diffoscope running, but there is
a pdftk in sleep mode.