apt-get source pkg=version downloads the wrong version

Binary package hint: apt

When specifying to download tdiary=2.2.1-1, it instead downloads 2.2.1-1.1. I use a local mirror.

$ apt-get source --only-source tdiary=2.2.1-1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Need to get 4,237kB of source archives.
Get:1 http://debmirror.../ubuntu/ lucid/universe tdiary 2.2.1-1.1 (dsc) [1,063B]
Get:2 http://debmirror.../ubuntu/ lucid/universe tdiary 2.2.1-1.1 (tar) [4,207kB]
Get:3 http://debmirror.../ubuntu/ lucid/universe tdiary 2.2.1-1.1 (diff) [28.8kB]
Fetched 4,237kB in 0s (11.5MB/s)
dpkg-source: info: extracting tdiary in tdiary-2.2.1
dpkg-source: info: unpacking tdiary_2.2.1.orig.tar.gz
dpkg-source: info: applying tdiary_2.2.1-1.1.diff.gz

2.2.1-1 is in intrepid, and this version is available in the mirror:
$ grep tdiary /var/lib/apt/lists/debmirror*_ubuntu_dists_intrepid_*Sources
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources:Package: tdiary
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources:Binary: tdiary, tdiary-theme, tdiary-plugin, tdiary-mode, tdiary-contrib
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources:Directory: pool/universe/t/tdiary
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: 8741303927eae48b22d19cbacfba8fa0 1046 tdiary_2.2.1-1.dsc
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: 41bd634fc4a8a6ffe93f70d33c826865 4207143 tdiary_2.2.1.orig.tar.gz
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: 2edde189e08f52b1ce4fff71ceb06774 31278 tdiary_2.2.1-1.diff.gz
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources:Homepage: http://www.tdiary.org/
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: cdd6d062dc5d9e4ed5eb512864e73052063c017c 4207143 tdiary_2.2.1.orig.tar.gz
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: f1562e5d0c6a7b4e6cc088b733dd4560df1e4c92 31278 tdiary_2.2.1-1.diff.gz
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: 897a593b0323d85e1bfa4bff6309d5e700e6203db0bf3bb4d8957888b7256bb2 4207143 tdiary_2.2.1.orig.tar.gz
./debmirror..._ubuntu_dists_intrepid_universe_source_Sources: cc80da811a78b86fce530d564322e41040ee182f86be70322839efdec90f05f0 31278 tdiary_2.2.1-1.diff.gz

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: apt 0.7.25.3ubuntu4
ProcVersionSignature: Ubuntu 2.6.32-17.26-generic 2.6.32.10+drm33.1
Uname: Linux 2.6.32-17-generic x86_64
Architecture: amd64
Date: Mon Mar 29 14:48:49 2010
EcryptfsInUse: Yes
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
SourcePackage: apt