Your script gives same error under Win32 and Strawberry; I installed latest IM 7.1.1-11 and then Image::Magick. Though they specifically warn:

Note, reading from or writing to a Perl filehandle may fail under Windows

maybe this plague has spread to Linux lately.

Reading from file (providing a filename) works. And this also works:

    my $i = Image::Magick-> new( magick => 'svg' );
    $i-> BlobToImage( do { undef $/; <DATA> } );
    $i-> Write( 'junk.png' );  # to test
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