/bin/sh -eu, unset parameters and heredocs

[Silas]

Hello.

See the following program:

    set -eu
    echo 1
    cat <<EOF
    $unset
    EOF
    echo 2

The output for /bin/sh (CVS HEAD) is:

    1
    sh: unset: parameter not set
    2

but the output for dash 0.5.11 is:

    1
    /opt/dash-0.5.11/bin/dash: 5: unset: parameter not set

and the output for bash --posix (5.0.17) is:

    1
    bash: line 5: unset: unbound variable

Should I file a PR?

Thanks!