6.4 doas gives "command not found" if no #!/bin/sh up top

Just upgraded from 6.3 to 6.4 and the doas behaviour seems to have changed.

I finally solved it, but just posting here in case anyone has this problem.

I had a few little shell scripts in /usr/local/sbin/ - intended to be run
by doas : one-liners like bioctl mounting a USB stick or whatever.

After upgrading to OpenBSD 6.4, all of them returned a "command not found"
error. I tried moving them to different paths in $PATH, but no luck.
Yet they'd work if I was root - just not via doas.

Adding a "#!/bin/sh" at the top of the scripts made them all work again.

Just FYI.

- Derek