Rename main branch to version3, version4 branch to main

[CharliePoole]

@nunit/engine-team
Actually, I'm debating whether to do this and looking for input

Reasons Pro...

• We're developing V3 and V4 at the same time, so only one can use main
• It's difficult to remember to always merge to Version4
• V4 merges do not auto-close
• The two have a slightly different directory structure, which may deviate further, giving you both sets of folders in the working directory unless you make a special effort.

Reasons con...

• It's a change from past practice with V2 and V3 (but not V1)
• It may be slightly more difficult to port changes from one to the other (although I often have had to rewrite them anyway)

The business with the directory structure has cost me a bit of time. If we keep the two in the same repo, I plan on setting up separate working directories and I'd suggest that for others as well.

I'd like to decide on this one way or the other rather quickly. How would you prefer to work?

[manfred-brands]

The only downside I see is the lack of cherry-picking.
It therefore depends on how much work we expect on V3. Only bug fixes or also possibly new features?
If the work on V3 is little, make V4 the main branch.

In these cases, I would have two cloned repo's locally. Like I have for nunit(.framework) V3 and V4. This allows working in separate branches and directories and comparing difference between versions, both in source and test outcomes.

So, I'm happy either way.

[CharliePoole]

Good point... we could move as much as needs to be moved and then switch main (again).

V3 - V4 ports are done through 3.16.2 AFAIK. Most of the ones I worked on couldn't be cherry-picked because the two branches had already diverged too much. I just looked at what had changed and adjusted it to fit. Even so, it's handy to have when you can use it.

I'll take a look at how much that's changed since 3.16.2 is relevant to V4 - many things may not be.

[CharliePoole]

We'll keep the same repo. I have renamed the issue to reflect the decision and marked it as blocked. We won't do it until we believe there will be no more minor 3.19 releases.