Our add-on developers would like to know which of their downloads are users and which are psi4 continuous integration bots. This is just a metapackage to track the latter, so use it in your travis.yml and the like. I regret that due to forces beyond my understanding, you probably have to specify psi4-lt-mp as well to get sensible version behavior for py27, so use the following for 1.1 and nightly build respectively.

conda create -q -n p4env ci-psi4-lt psi4-lt-mp -c psi4

conda create -q -n p4env ci-psi4-lt psi4-lt-mp -c psi4/label/dev -c psi4