User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.132 Safari/537.36
Steps to reproduce:
(I encountered this issue when building mozjs 60.9.0esr, but checked HEAD at https://dxr.mozilla.org/mozilla-central/source/build/moz.configure/old.configure#132 and it’s still present.)
On my system, all programs are wrapped by a small program that sets relevant environment variables to ensure that same dependencies are used as were present at build time (“hermetic packages”, I have a blog post upcoming in case anyone is interested).
This generally works fine, but I encountered an issue when building mozjs (for polkit): build/moz.configure/old.configure assumes that autoconf is a shell script (it isn’t on my machine) and runs [shell, autoconf], which fails.
The firefox build system tried to run autoconf via the shell.
autoconf should have been run directly, without an explicit shell in between.