First Wix took code licensed under the GNU GPL, used it to enhance their code and shipped the combined work under a license not compatible with the GNU GPL, violating the rights of copyright holder Automattic.
Now, they’ve taken code distributed under the MIT license, very permissive, and relicensed under a new license they created ad-hoc. They call the new license “The Enhanced MIT License”, which is exactly like the MIT License, with one exception:
Any distribution of this source code or any modification thereof in source code format, must be done under the Enhanced MIT license and not under any other licenses, such as GPL.
The license file is basically a political manifesto against the copyleft licenses (like the GNU GPL), where they use the derogatory adjective ‘viral’ to describe the persistent nature of the four freedoms granted by the license.
Does this EMIT license conform to the definition of open source? Maybe… but my smell test says this is a messy license. In the “Official wording” section (the part in legalese) I read:
the licensee is prohibited to change the license of the Software to any “viral” copyleft-type license
But in the FAQ above they say:
if you add/change the source code, the license must be kept as Enhanced MIT license.
which is not the same thing. Has this been reviewed by an attorney? Until it has, I wouldn’t touch this code with a 10-foot pole.