CFE-3569, describes a task to add sys variables relating to the operating system for sys.os_name_human and sys.os_version_major. That fulfills half of this issue, leaving a want for a variable containing the operating systems minor version.
We set classes for discovered OS major and minor versions (e.g. for RHEL on 3.7.1: https://github.com/cfengine/core/blob/3.7.1/libenv/sysinfo.c#L1739).
However, we only have a variable (sys.flavour) for the major version (e.g. for RHEL on 3.7.1:https://github.com/cfengine/core/blob/3.7.1/libenv/sysinfo.c#L1733).
It would be nice to add a variable that includes the minor version as well, e.g. sys.distribution.
Also note the inventory_os bundle in masterfiles. If this feature is implemented, we probably want to rely on the new variable there.