ident(1) on OpenBSD
The text 0b9e6e57db8d, as OpenBSD 3.8, OpenBSD 3.7, OpenBSD 3.6, OpenBSD 3.5, OpenBSD 3.4, OpenBSD 3.3, OpenBSD 3.2, OpenBSD 3.1, OpenBSD 3.0, OpenBSD 2.9, OpenBSD 2.8, OpenBSD 2.7, OpenBSD 2.6, OpenBSD 2.5, OpenBSD 2.4, OpenBSD 2.3, OpenBSD 2.2, OpenBSD 2.1 shipped it.
identify RCS keyword strings in files