$ tail /usr/share/bash-completion/completions/primecoind.bash-completion
complete -F _bitcoind bitcoind
Also, the filename should be 'primecoind' (matching the completed executable) -- or rather 'bitcoind' in this case ;P.
Oh, and while at it, please remove USE=bash-completion. Completions are supposed to be installed unconditionally.
The same applies to litecoind and datacoin-hp. Also, the 'have' inside is deprecated :).
I did a simple sed on the bash-completion's. This appears to be sufficient. As far as the 'have' goes, i found at least 190 on my system alone that use it. If we want to deal with them, we might open a tracker with instructions on what to use instead.