at time of writing, spotify (in this particular repo) was at version spotify-client-qt_0.6.2.291.gcccc1f5.116-1_amd64.deb & i386.deb

so after installing the piczu overlay to install spotify on my machine i noticed that it was not finding the appropriate file in the proper repo uri (http://repository.spotify.com/pool/non-free/s/spotify).

it was searching for $REPO_URI/spotify-client-qt-ver.ga662380-1_i386.deb

here is the ebuild (spotify-0.4.6.73.ebuild) as provided by piczu’s overlay:

# Copyright 1999-2010 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

EAPI="3"

inherit eutils

MY_PN="spotify-client-qt"
MY_PV="${PV}.ga662380"
MY_P="${MY_PN}_${MY_PV}"

DESCRIPTION="A proprietary peer-to-peer music streaming desktop application"
HOMEPAGE="http://www.spotify.com"
REPO_URI="http://repository.spotify.com/pool/non-free/s/spotify"
SRC_URI="amd64? ( ${REPO_URI}/${MY_P}-1_amd64.deb )
    x86? ( ${REPO_URI}/${MY_P}-1_i386.deb )"

LICENSE="Spotify"
SLOT="0"
KEYWORDS="~amd64 ~x86"
IUSE=""

# media-sound/asoundconf left
DEPEND=""
RDEPEND="${RDEPEND}
    >=x11-libs/qt-dbus-4.5.0
    >=x11-libs/qt-webkit-4.5.0
    >=x11-libs/qt-core-4.5.0
    >=x11-libs/qt-gui-4.5.0"

src_unpack() {
    unpack ${A} ./data.tar.gz
}

src_install() {
    insinto /opt/${PN}
    into /opt/${PN}
    dobin usr/bin/spotify
    dosym /opt/${PN}/bin/spotify /usr/bin/spotify
    newdoc usr/share/doc/spotify-client-qt/changelog.Debian.gz changelog.gz
        doins -r usr/share/spotify/theme
    # hardcoded path fix
    dodir /usr/share/spotify
    dosym /opt/${PN}/theme /usr/share/spotify/theme
}

here are the changes i made to it :

# Copyright 1999-2010 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

EAPI="3"

inherit eutils

MY_PN="spotify-client-qt"
#MY_PV="${PV}.ga662380"
MY_PV="${PV}.gcccc1f5.116-1"
MY_P="${MY_PN}_${MY_PV}"

DESCRIPTION="A proprietary peer-to-peer music streaming desktop application"
HOMEPAGE="http://www.spotify.com"
REPO_URI="http://repository.spotify.com/pool/non-free/s/spotify"
SRC_URI="amd64? ( ${REPO_URI}/${MY_P}_amd64.deb )
    x86? ( ${REPO_URI}/${MY_P}_i386.deb )"

LICENSE="Spotify"
SLOT="0"
KEYWORDS="~amd64 ~x86"
IUSE=""

# media-sound/asoundconf left
DEPEND=""
RDEPEND="${RDEPEND}
    >=x11-libs/qt-dbus-4.5.0
    >=x11-libs/qt-webkit-4.5.0
    >=x11-libs/qt-core-4.5.0
    >=x11-libs/qt-gui-4.5.0"

src_unpack() {
    unpack ${A} ./data.tar.gz
}

src_install() {
    insinto /opt/${PN}
    into /opt/${PN}
    dobin usr/bin/spotify
    dosym /opt/${PN}/bin/spotify /usr/bin/spotify
    newdoc usr/share/doc/spotify-client-qt/changelog.Debian.gz changelog.gz
        doins -r usr/share/spotify/theme
    # hardcoded path fix
    dodir /usr/share/spotify
    dosym /opt/${PN}/theme /usr/share/spotify/theme
}

I also removed the existing manifest and the old ebuilds and just generated a new one from this ebuild file.
this ebuild file was named spotify-0.6.2.291.ebuild to match the version that is in the repo.
the manifest file was created by running ebuild spotify-0.6.2.291.ebuild manifest