Race condition in run-program

Trying the new run-program in ECL 16.0.0 (git:b2661fd1) with ASDF 3.1.5.6, I find that tests that use run-program fail. I tried to investigate test-run-program.script, and found what is likely a race condition, that decreases when I trace things (maybe giving more time for the other process to die properly and be reaped before Lisp proceeds?).

make -C ~/cl/asdf/ l=ecl t='test-run-program.script test-program.script test-sysdef-asdf.script' t

Also, redirecting to a file doesn't seem to work. Is it supposed to?