Here is an interesting case: A company provides a free (MPL-licensed) library (called JointJS), and furthermore a number of proprietary extensions (called rappid).On their web server they ship a file that combines code from both parts of the library at http://jointjs.com/js/joint.all.min.js (gist for historical reference), as it is quite common for JavaScript libraries. But note that this file contains only a copyright or license statement for the free JointJS part (and a few other free licenses for third-party tools). So the structure of the file is:/*! JointJS v0.9.3 - JavaScript diagramming library  2015-06-26 This Source Code Form is subject to the terms of the Mozilla PublicLicense, v. 2.0. If a copy of the MPL was not distributed with thisfile, You can obtain one at http://mozilla.org/MPL/2.0/. */[Similar license header for first third-party library][first third party library][Similar license header for second third-party library][second third party library][JointJS code (likely intended to be released under the MPL][rappid code (when separately distributed, not released under the MPL]So assuming I were pointed to that file only (as you are now), there is no way of knowing that parts of that code are not intended to be licensed under the MPL license as stated. And given that fact that the actual copyright owner did that, does this imply that all parts of that file can now be used under the terms of the JointJS part itself?
Are ambiguous JavaScript concatenations by the copyright owner legally significant
mit;license notice;release
The license explicitly claims to apply to the source code. A concatenation of files is not source code by the usual definition: it is not the original file that would normally be modified, but a mechanically-constructed derivative that just happens to be somewhat human-readable. Thus the text you cite does not in fact apply to the file at all.You could make an argument that the inclusion of the license text is misleading, and that you believed that this file was the source code. After all, how were you to know that the file was mechanically generated? (Or even granting that it was at some point, the result might then have been misguided manually.) The onus is generally on the party that writes the contract to make it clear, so that ambiguities benefit the other party. That would only fly if you'd never read this thread, of course.