It looks there is an order-only prerequisite in elfhack's Makefile: https://mxr.mozilla.org/mozilla-central/source/build/unix/elfhack/Makefile.in#124
Unfortunately, PyMake doesn't support order-only prerequisites. The offending rule should be rewritten to not use order-only prerequisites so PyMake can parse it.
Created attachment 649577 [details] [diff] [review]
Use mkdir_deps instead of order-only prerequisite in build/unix/elfhack/Makefile.in