This tests for a bug with an empty option

Originally, the empty option was accepted / ignored when at the end of
the last connection:

    conn last
        rightsubnet=

but fails when at the end of the non-last connection:

    conn last
        rightsubnet=
    conn reallast
        ...

However, that is "fixed" in that this rule:

	| KEYWORD EQUAL { /* this is meaningless, we ignore it */ }

which is part of the grammer is able to always accept an empty option.

Question now is, is that valid?
