Add an issue boilerplate for asking about unclear GPL3-like license

[roberth]

If it isn't clear from the code, nothing beats an answer from the authors. However, they may be unprepared for the question, so it'd be helpful for us to have a boilerplate question to send them that is

• is clear
• explains the relevance of the question to others
• explains our motivation
• is polite and understanding

Perhaps someone has already asked such a question and they could share their experience?

The resulting text could be added to https://github.com/jtojnar/nixpkgs-hammering/blob/master/explanations/unclear-gpl.md for copy, paste and modification by whoever needs it. Having a central place for this kind of thing, we can keep improving our public presence.

[jtojnar]

Good idea.

I typically search for earlier issues I opened:

• https://github.com/rime/ibus-rime/issues/107
• https://github.com/fossar/selfoss/issues/1218
• https://github.com/solvespace/solvespace/issues/943
• https://github.com/dialect-app/dialect/issues/4
• https://github.com/AltraMayor/f3/issues/148
• https://gitlab.com/vala-panel-project/vala-panel-appmenu/-/issues/331

But having a specific template would be nice.

It is made complicated by the fact that without clarification one could interpret the license as being *-only so the project might need to ask all past contributors to agree with relicensing to be legally in the clear (see the selfoss example).

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I did not know about this:

If the Program does not specify a version number of the GNU General Public License, you may choose any version ever published by the Free Software Foundation.

But it is not clear what does it mean for program to specify a version number. If they include the license text in the COPYING file as recommended by the license, the version is listed at the top so I would expect that to count as being specified.