The Clinton campaign debated whether to come out against the Keystone XL pipeline in August 2015 as a way to turn attention away from her secret email server and the bad press she was generating, according to messages hacked from her campaign chairman’s account and released Monday by WikiLeaks. ... The campaign’s willingness to use Keystone to shift attention from Mrs. Clinton’s troubles over her secret email server is a signal of just how troublesome those emails were.