FTBFS the second time

$ apt-get source unity-greeter
$ cd unity-greeter-0.2.0
$ dpkg-buildpackage -b

(first build completes successfully)

$ dpkg-buildpackage -b

/.../
configure: exit 1
dh_auto_configure: ./configure --build=x86_64-linux-gnu --prefix=/usr --includedir=${prefix}/include --mandir=${prefix}/share/man --infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var --libexecdir=${prefix}/lib/unity-greeter --disable-maintainer-mode --disable-dependency-tracking returned exit code 1
make: *** [build] Fel 25
dpkg-buildpackage: fel: debian/rules build returnerade felkod 2

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: unity-greeter 0.2.0-0ubuntu6
ProcVersionSignature: Ubuntu 3.2.0-14.23-generic 3.2.3
Uname: Linux 3.2.0-14-generic x86_64
ApportVersion: 1.91-0ubuntu1
Architecture: amd64
Date: Fri Feb 10 15:19:43 2012
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120103)
SourcePackage: unity-greeter
UpgradeStatus: No upgrade log present (probably fresh install)