rubinius/rubinius — pull request #1905 by tonysidaway (2012-09-16 17:51:54+00:00)
Title: Discard OpenBSD release number in config[:os]

The rationale for this is as follows.

OpenBSD has a continuous evolution release model. The release numbers change twice a year like clockwork and reflect the release process phases rather than revolutionary changes of the platform (which are intentionally kept to a minimum). The system probably doesn't change radically enough to merit a release number in the os name here. OpenBSD is OpenBSD.

http://www.openbsd.org/papers/asiabsdcon2009-release_engineering/mgp00017.html

Notice also that the release number does not follow the major/minor convention, for obvious reasons. Release 5.0 was simply the next release after 4.9.