Comment 3 for bug 1394469

Nothing in the definition of /etc/os-release requires that this field be updated for point releases. It is Ubuntu policy to not update the machine-readable field in this file (and in /etc/lsb-release), because software *should not* treat point releases differently than they treat the original release. If there is a need to treat the releases differently, it should be on the basis of specific packages that are installed (or not), which you would check with dpkg, not with /etc/os-release.