[kiwidrew]

The pledge(2) manpage for 6.2 and earlier states:

"BUGS. The path whitelist feature is not available at this time."

So the second argument was previously unused, and thus could be repurposed without hurting backwards compatability.

[ams6110]

zokier's point is still correct though. OpenBSD is a complete system, kernel + userland. You upgrade in lockstep.