lalpulsar 7.1.1 build for Debian 13 Trixie fails on arm64

Although Debian builds were successful for amd64 (Bullseye/Bookworm/Trixie) and arm64 (Bullseye/Bookworm), I'm repeatedly facing a strange error Unable to popen(3) in test_hwinject when attempting to build lalpulsar 7.1.1 in Debian 13 Trixie on arm64.

The full log is here: https://hypatia.aei.mpg.de/lsc-arm64-trixie/lalpulsar_7.1.1-1+deb13u0_arm64.--pbuilderlog

Any suggestions how to narrow this down (and possibly fix) are appreciated.