Double extraction of toolset source archives

The adjust configurations is called twice which was introduced by commit

cb3bb6c77ce0f885f9bd618e998d464b65f75edc

and consequently the addToolsets is also called twice. This will cause the sources to be unpacked twice when building with selected configurations.

agent:2017/06/13 13:14:26 build.go:344: Executing instruction 13 of 24
agent:2017/06/13 13:14:26 storageclient.go:418: Unpacking binaries "/home/vmbuilder/ci-working-dir/storage/yocto/meta-boot2qt/b9522b7fe416f97d3b5c56d6f433beaf9da72d3e/LinuxUbuntu_16_04x86_64LinuxBoot2Qt_Jethrox86_64GCCqtci-linux-Ubuntu-16.04-x86_64-844791DisableTests/7ca30f915833d953146007e71743147e3e719500/build_1496839555/artifacts.tar.gz" in "/home/qt/work"
agent:2017/06/13 13:15:01 build.go:344: Executing instruction 14 of 24
agent:2017/06/13 13:15:01 storageclient.go:381: Unpacking sources "/home/vmbuilder/ci-working-dir/storage/qt/qtqa/a8269470a9e21f3e685f25c09e3a92f0ac6615d5/sources_unix.tar.gz" in "/home/qt/work/qt/qtqa-latest"
agent:2017/06/13 13:15:02 build.go:344: Executing instruction 15 of 24
agent:2017/06/13 13:15:02 storageclient.go:418: Unpacking binaries "/home/vmbuilder/ci-working-dir/storage/yocto/meta-boot2qt/b9522b7fe416f97d3b5c56d6f433beaf9da72d3e/LinuxUbuntu_16_04x86_64LinuxBoot2Qt_Jethrox86_64GCCqtci-linux-Ubuntu-16.04-x86_64-844791DisableTests/7ca30f915833d953146007e71743147e3e719500/build_1496839555/artifacts.tar.gz" in "/home/qt/work"
agent:2017/06/13 13:15:02 retry.go:24: Operation failed with an error: symlink /bin/chattr.e2fsprogs /home/qt/work/b2qt/toolchain/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi/bin/chattr: file exists

https://testresults.qt.io/coin/logview/qt/qtquickcontrols/b7d3779dfe7f4a48ddf27d84725c537db571ecc2/LinuxUbuntu_16_04x86_64LinuxBoot2Qt_Jethrox86_64GCCqtci-linux-Ubuntu-16.04-x86_64-844791DisableTests/4daacd38966b55e5709918958a670f34766debb0/build_1497352852/buildlog.txt.gz