I have a hand-written pdf parser I like to use which takes several
command line options, if I use a configuration file like:

    external_parsers: \
        application/pdf "/usr/local/bin/docweight"

everything works as advertised; pdf's get indexed and show up in the
search results.  However, if I use a line like:

    external_parsers: \
        application/pdf "/usr/local/bin/docweight -d -t 'PDF Document'"

htdig doesn't index any pdfs, and gives this strange error when indexing
the site (with a -vvvv):

    "External parser error: unknown field in line Read 8192 from document"

Which is strange considering none of my PDF's are over 800 lines and
there's no line number "Read 8192" either.  This all was working at some
point in the past, however 3.1.6 seems to have broken the external
parser code.