Good spot. Looking at the repo, the Packages list only seems to have these:
Package: tvheadend
Version: 4.0.3~precise
Architecture: amd64
Maintainer: Andreas Öman <andreas@tvheadend.org>
Installed-Size: 24130
Depends: libavahi-client3 (>= 0.6.16), libavahi-common3 (>= 0.6.16), libc6 (>= 2.15), libdbus-1-3 (>= 1.0.2), libdvbcsa1 (>= 1.1.0), libssl1.0.0 (>= 1.0.0), liburiparser1 (>= 0.6.0), zlib1g (>= 1:1.1.4)
Recommends: xmltv-util
Enhances: showtime
Replaces: hts-tvheadend
Section: video
Priority: extra
Homepage: https://tvheadend.org
Description: Tvheadend
Tvheadend is a TV streaming server for Linux supporting DVB, ATSC, IPTV, and Analog video (V4L) as input sources.
Can be used as a backend to Showtime, XBMC and various other clients.
Filename: pool/main/t/tvheadend/tvheadend_4.0.3~precise_amd64.deb
SHA1: 5ba2c45ff5c618186cf7b8a0e5f11859dc20e9e7
Size: 9493208
Package: tvheadend
Version: 4.0.4~trusty
Architecture: amd64
Maintainer: Andreas Öman <andreas@tvheadend.org>
Installed-Size: 24134
Depends: libavahi-client3 (>= 0.6.16), libavahi-common3 (>= 0.6.16), libc6 (>= 2.15), libdbus-1-3 (>= 1.0.2), libdvbcsa1 (>= 1.1.0), libssl1.0.0 (>= 1.0.0), liburiparser1 (>= 0.6.0), zlib1g (>= 1:1.1.4)
Recommends: xmltv-util
Enhances: showtime
Replaces: hts-tvheadend
Section: video
Priority: extra
Homepage: https://tvheadend.org
Description: Tvheadend
Tvheadend is a TV streaming server for Linux supporting DVB, ATSC, IPTV, and Analog video (V4L) as input sources.
Can be used as a backend to Showtime, XBMC and various other clients.
Filename: pool/main/t/tvheadend/tvheadend_4.0.4~trusty_amd64.deb
SHA1: 66c43ad7b060b655fa5786457621a49cf5c6e937
Size: 9492092
Package: tvheadend
Version: 4.0.5~trusty
Architecture: amd64
Maintainer: Andreas Öman <andreas@tvheadend.org>
Installed-Size: 24134
Depends: libavahi-client3 (>= 0.6.16), libavahi-common3 (>= 0.6.16), libc6 (>= 2.15), libdbus-1-3 (>= 1.0.2), libdvbcsa1 (>= 1.1.0), libssl1.0.0 (>= 1.0.0), liburiparser1 (>= 0.6.0), zlib1g (>= 1:1.1.4)
Recommends: xmltv-util
Enhances: showtime
Replaces: hts-tvheadend
Section: video
Priority: extra
Homepage: https://tvheadend.org
Description: Tvheadend
Tvheadend is a TV streaming server for Linux supporting DVB, ATSC, IPTV, and Analog video (V4L) as input sources.
Can be used as a backend to Showtime, XBMC and various other clients.
Filename: 4.0.5/pool/main/t/tvheadend/tvheadend_4.0.5~trusty_amd64.deb
SHA1: 4a847d53a055e18f3d72ff972b2faedecb899258
Size: 9492898
Package: tvheadend-dbg
Source: tvheadend
Version: 4.0.3~precise
Architecture: amd64
Maintainer: Andreas Öman <andreas@tvheadend.org>
Installed-Size: 21222
Depends: tvheadend (= 4.0.3~precise)
Section: debug
Priority: extra
Description: Debug symbols for Tvheadend
This package contains the debugging symbols for Tvheadend.
Filename: pool/main/t/tvheadend/tvheadend-dbg_4.0.3~precise_amd64.deb
SHA1: 56adba319c5371cea255f654ea6848e7a6f3cac6
Size: 4246236
Package: tvheadend-dbg
Source: tvheadend
Version: 4.0.4~trusty
Architecture: amd64
Maintainer: Andreas Öman <andreas@tvheadend.org>
Installed-Size: 21221
Depends: tvheadend (= 4.0.4~trusty)
Section: debug
Priority: extra
Description: Debug symbols for Tvheadend
This package contains the debugging symbols for Tvheadend.
Filename: pool/main/t/tvheadend/tvheadend-dbg_4.0.4~trusty_amd64.deb
SHA1: 497953af2b312a7cfc860f00e66cba31b5c4c9af
Size: 4247498
Package: tvheadend-dbg
Source: tvheadend
Version: 4.0.5~trusty
Architecture: amd64
Maintainer: Andreas Öman <andreas@tvheadend.org>
Installed-Size: 21223
Depends: tvheadend (= 4.0.5~trusty)
Section: debug
Priority: extra
Description: Debug symbols for Tvheadend
This package contains the debugging symbols for Tvheadend.
Filename: 4.0.5/pool/main/t/tvheadend/tvheadend-dbg_4.0.5~trusty_amd64.deb
SHA1: 516ed6ab5dab65ea07bb6dfe0c7c3ad7fccbd252
Size: 4248748
... which matches your list of candidates. Might be that there's a repository problem, let me try to raise it.
4.0.6
is listed in the 'testing' repo, which may be deliberate - but it sounds more like it should be a stable release, though.