Currently, non-tagged binaries are assumed to be old (pre-ELFv2) and kernel supply them with auxv in old format (because it can't extract OSREL from these binaries).
This cause problems for non-tagged programs expecting the new auxv format.
An example is rtld, that is not tagged. When using direct exec mode, old format auxv is passed to it, that forwards auxv to the binary to be run.
If it expects the new auxv format, as is the case for -CURRENT, it usually crashes early.
Besides rtld, this could also happen with binaries compiled in non-standard forms or when using compilers built outside base/ports.
This change makes the kernel assume that non-tagged binaries want the new auxv format.
While this may break direct exec'ing old binaries, it seems more appropriate, considering that the transition to ELFv2 happened several months ago in -CURRENT.
IMHO, a user running the latest kernel and world binaries would expect the new auxv format to be used, matching the installed binaries of his base system.
Note: perhaps printing a warning message when default is assumed would be nice.