Dear Guillem, dh-make-elpa imports a lot of subroutines directly from dh-make-perl. So it uses libdebian-source-perl because that's the representation used in dh-make-perl.
dh-elpa uses libdebian-source-perl simply because when I added the functionality that requires it, I'd just written dh-make-elpa, and it didn't occur me to look for the functionality in libdpkg-perl. dh-elpa uses libdebian-source-perl only to see whether the Build-Depends field contains a certain binary package. HTH! -- Sean Whitton
