Merge only_www_touched change from validate.py

Do not build/check all books if only www/ is changed, instead
abort early.
This is a merge of a change only done for validate.py.

Change-Id: If81ee7c89c79e6571e2deebd98f6f596260d56c7
fixes incorrect link in lead page

underconstruction page had a create new commit link that was linking to the create branch page instead.

bug/1226359

Change-Id: I2ef6b6000eba9a7059d7694e4ddee56cdfdc9039
Merge "fixes incorrect link in lead page"
Merge "Merge only_www_touched change from validate.py"