We are part of a startup company that's forking nxt at 8cd423eee becaise the MIT license suits us better. Since the license changed to GPL...
Starting from this commit would be a copyright violation. The last release done under MIT was 1.5.6e, dated 2015-04-28. It was also a closed source release, meaning you have to base your work on that closed source (i.e. a decompiled and deobfuscated version of it).
Releases 1.5.7e and 1.5.8e were done under a temporary experimental releases license, which prohibits their use, or the use of any software based on them, after June 30, 2015. The MIT license never applied to those releases, only to parts of them already published in previous versions.
Release 1.5.9 was the first release done under the GPL, on 2015-05-26, and the first publication of the 1.5 branch source code. No 1.5
source code has been released before that date, and no 1.5
source code has been released under a license other than the GPL. You cannot look back at the commit log and decide by those dates which change is under GPL and which is not, because none of that source was released to the public until the date of release of 1.5.9, and at that time it was all released under GPL.
To make my point more obvious, if I start writing some software from scratch, and only add the GPL license file at the end, and then publish it all, you cannot just go read the timestamps on each commit and argue that the GPL does not apply to the files committed before the addition of the LICENSE.txt file. This is essentially what you are trying to do. Those intermediate commits were never pushed one by one to the public master branch, as we never publish the source of experimental releases. When the source is finally published, it is published together with the license that applies to it, and it applies to the source as a whole, regardless of the commit timestamp on each individual file.
So if you are a developer and ascribe value to this work, we hope you will license your commits as a MIT, and we will try as best as possible to reconcile those commits with our tree without violating anyone's GPL code.
The work of core developers is accepted only under GPL, there will be no more "MIT commits" to the core.