'kpdf' should be deleted from the end of the line #88 in /etc/bash_completion, since it is now redefined in the line #84.
That means,
complete -f -X '!*.@(pdf|PDF)' acroread gpdf xpdf kpdf
should now be
complete -f -X '!*.@(pdf|PDF)' acroread gpdf xpdf
'kpdf' should be deleted from the end of the line #88 in /etc/bash_ completion, since it is now redefined in the line #84.
That means,
complete -f -X '!*.@(pdf|PDF)' acroread gpdf xpdf kpdf
should now be
complete -f -X '!*.@(pdf|PDF)' acroread gpdf xpdf