The second test rebuild of Yakkety Yak was started on September 16 for all architectures, all components (main component and seeded packages mostly finished, unseeded packages still building).
Results (please also look at the superseded builds) can be found at
http://qa.ubuntuwire.org/ftbfs/test-rebuild-20160916-yakkety.html
Additional build failures for packages in yakkety-proposed (not yet in yakkety) can be found at http://qa.ubuntuwire.com/ftbfs/
Please help fixing the build failures.
Another test rebuild using the Linaro-GCC 6 as the default (planning the defaults change around the end of October) can be found at
http://qa.ubuntuwire.org/ftbfs/test-rebuild-20160916-linaro-yakkety.html
The corresponding compiler can be found in the ubuntu-toolchain-r/test PPA.
Matthias