multistrap fails when aptsources not specified

multistrap fails when aptsources is not specified within multistrap.conf:

    # multistrap -f multistrap-occmp.conf 
    >> multistrap 2.1.7 using multistrap-occmp.conf
    >> multistrap: No sources defined for a foreign multistrap.
    >>         Using your existing apt sources. To use different sources,
    >>         list them with aptsources= in 'multistrap-occmp.conf'.
    >> Using foreign architecture: powerpcspe
    >> multistrap building powerpcspe multistrap on 'i386'
    >> INF: Setting ./lib64 -> ./lib symbolic link.
    >> Getting package lists: apt-get  -o Apt::Architecture=powerpcspe -o Dir::Etc::TrustedParts=/homes/nfs/multistrap/chroot/etc/apt/trusted.gpg.d -o Dir::Etc::Trusted=/homes/nfs/multistrap/chroot/etc/apt/trusted.gpg -o Apt::Get::AllowUnauthenticated=true -o Apt::Get::Download-Only=true -o Apt::Install-Recommends=false -o Dir=/homes/nfs/multistrap/chroot/ -o Dir::Etc=/homes/nfs/multistrap/chroot/etc/apt/ -o Dir::Etc::SourceList=/homes/nfs/multistrap/chroot/etc/apt/sources.list.d/multistrap.sources.list -o Dir::State=/homes/nfs/multistrap/chroot/var/lib/apt/ -o Dir::State::Status=/homes/nfs/multistrap/chroot/var/lib/dpkg/status -o Dir::Cache=/homes/nfs/multistrap/chroot/var/cache/apt/ update
    >> E: Type 'ARRAY(0xa098de0)ARRAY(0xa098de0)' is not known on line 1 in source list /homes/nfs/multistrap/chroot/etc/apt/sources.list.d/multistrap.sources.list
    >> E: Type 'ARRAY(0xa098de0)ARRAY(0xa098de0)' is not known on line 1 in source list /homes/nfs/multistrap/chroot/etc/apt/sources.list.d/multistrap.sources.list
    >> E: The list of sources could not be read.
    >> apt update failed. Exit value: 100
    # cat /homes/nfs/multistrap/chroot/etc/apt/sources.list.d/multistrap.sources.list
    >> ARRAY(0xa098de0)ARRAY(0xa098de0)

As the embedded system i'm thinking of will not be allowed to be updated by apt 
i think it should be valid not to specify any update repositories, isn't it?
Or do i have a wrong understanding of aptsources?


Rüdiger