The License: field for zsh says BSD. 

Substantially all the source code for zsh is covered by the following terms (apart from the identified licensor):

 Permission is hereby granted, without written agreement and without
 licence or royalty fees, to use, copy, modify, and distribute this
 software and to distribute modified versions of this software for any
 purpose, provided that the above copyright notice and the following
 two paragraphs appear in all copies of this software.

 In no event shall the Zsh Development Group be liable to any party for
 direct, indirect, special, incidental, or consequential damages arising out
 of the use of this software and its documentation, even if the Zsh
 Development Group have been advised of the possibility of such damage.

 The Zsh Development Group specifically disclaim any warranties, including,
 but not limited to, the implied warranties of merchantability and fitness
 for a particular purpose.  The software provided hereunder is on an "as is"
 basis, and the Zsh Development Group have no obligation to provide
 maintenance, support, updates, enhancements, or modifications.

The style of this license places it in the group that Fedora has by convention been classifying as "MIT". (Of the MIT variants collected at https://fedoraproject.org/wiki/Licensing/MIT, it is rather similar to the Postgresql license.)