dash -i -c may prompt for input from stdin/terminal

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sh.html#tag_20_117_06 says:

> The standard input shall be used only if one of the following is true:
> * The -s option is specified.
> * The -c option is not specified and no operands are specified.
> * The script executes one or more commands that require input from
> standard input (such as a read command that does not redirect
> its input).

However, if you run:

    dash -i -c 'if'

then dash will drop to a prompt waiting for input from the terminal/stdin (after printing an error message for the legitimate syntax error. It should simply exit.

Another way to test this:

    dash -i -c 'read foo'

and then hit Ctrl-C. It will drop to a prompt when it should exit.