Can True Strike grant advantage to Witch Bolt?

Question

Since both True Strike and Witch Bolt require concentration, can True Strike grant advantage to Witch Bolt's attack roll?

My answer to this question received a comment saying that Witch Bolt's attack roll wouldn't get advantage from True Strike since they are both Concentration spells. The point piqued my interest, and since I've seen True Strike used to grant advantage to Witch Bolt at my table and on this answer, I wanted to raise the question.

As I see it, it's one of the two:

1. In order to cast Witch Bolt you need to stop concentrating on True Strike, so you don't get advantage.

2. You stop concentrating on True Strike as you cast Witch Bolt, so you get the advantage.

I believe here RAI would side with (2) while RAW sides with (1), but I would like a definitive, objective RAW answer. Any commentary from an authority that would provide a definite RAI ruling would be appreciated, too.

I thought about making this a more general question, like "Can a concentration spell affect the casting of another concentration spell?", but I believe a specific test case can help focus the answer and most likely any rulings on this specific case would apply to the general case, unless otherwise explicitly specified.

Time saver:

True Strike: On your next turn, you gain advantage on your first attack roll against the target, provided that this spell hasn’t ended.

Answer 1

In short, no.

The core question is what exactly defines concentration? According to roll20's compendium:

Some spells require you to maintain concentration in order to keep their magic active. If you lose concentration, such a spell ends... Normal activity, such as moving and attacking, doesn’t interfere with concentration. The following factors can break concentration:

Casting another spell that requires concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can’t concentrate on two spells at once...

By virtue of casting another spell that requires concentration, True Strike immediately ends, as do any and all effects caused by it. The caveat at the end of the description for True Strike actually sums it up nicely: provided that this spell hasn’t ended.

This little tidbit from Jeremy Crawford actually asks precisely the same question, and Mr. Crawfords answer is the same: as soon as another spell requiring concentration is cast, the first spell (and all effects) immediately end.

Answer 2

The answer should be yes, I think. True Strike takes one round of concentration; on the start of the next turn, if concentration has been held, the advantage to the first attack roll is granted, and concentration ends. Now it is time for the player's action. This is exactly why the spells takes one round; it ends on the start of the next turn when it grants the advantage.

IC it makes sense as well, you concentrate for one round to gain the insight in opponent's defenses mentioned in the description. Then you drop concentrating on that and strike.

The question is not whether you can cast a concentration spell while concentrating on something else (such as Bless or Shadow Blade) because no, you can't. The question is whether True Strike ends after one round and grants the advantage, or continues for another round and keeps demanding concentration.