I do not know of a need to have the default shell be a build-time
configurable setting. All *nix systems I am aware of have /bin/sh as a
default posix compatible shell.
If some systems running OpenRC do not make that assumption about
/bin/sh, I will consider bringing this back, so feel free to open an
issue.
Sysvinit shutdown has a default of single user mode, but openrc-shutdown
makes you choose a default action. Because of this, the shutdown wrapper
needs to pass --single to openrc-shutdown.
