Comment 18 for bug 1633180

In some Ubuntu distributions very old and somewhat buggy mawk is still the default awk, and gawk is not installed. gawk may also be a dependency of some packages you have installed. If you have many implementations installed, you can choose the default one by
sudo update-alternatives --config awk
You could get more recent awk from http://invisible-island.net/mawk/mawk.html
and try, if the script works better with a more recent mawk.