-r ./base.txt
sphinx==1.5.4
alabaster==0.7.10
releases==1.3.0  # updated from 1.2.1

-r ./base.txt
sphinx==1.5.5
alabaster==0.7.10
releases==1.3.0  # updated from 1.2.1

Update sphinx from 1.5.4 to 1.5.5
Update sphinx from 1.5.4 to 1.5.5