Before = dpv: <__func__>: posix_spawnp(3): No such file or directory
After = dpv: <path/cmd>: No such file or directory
Most notably, show the 2nd argument being passed to posix_spawnp(3)
so we know what path/cmd failed.
Also, we don't need to have "posix_spawnp(3)" in the error message
nor the function because that can [a] change and [b] traversed using
a debugger if necessary.
cfeecda0a9