I suspect this will be the usual case (and not OpenBSD-specific), given that install-sh is part of the distribution and all of this was generated by autoconf/automake.
This means that all that is accomplished by the present check in practice is to test whether the shell exists and is executable.
Correction: The argument of -m in my case ended up being:
/bin/sh /.../geda- gaf-1.10. 2/build- tools/install- sh -d
I suspect this will be the usual case (and not OpenBSD-specific), given that install-sh is part of the distribution and all of this was generated by autoconf/automake.
This means that all that is accomplished by the present check in practice is to test whether the shell exists and is executable.