Revert "run interpolation after merge, but for required attributes"

[idsulik]

This reverts commit 65600ce.

The commit led to this issue docker/compose#12001, a quick fix is to revert the commit and release it.

[ndeloof]

We only do such revert if there's no reasonable fix to offer.
For those impacted it is easy to just keep running older docker compose release

[idsulik]

We only do such revert if there's no reasonable fix to offer. For those impacted it is easy to just keep running older docker compose release

Okay, I got it. It was just a quick fix. I think it'll be better to revert and release if we don't be able to fix it asap, because more and more users download the latest version and a lot of them will be forced to downgrade or spent time figuring out what went wrong

[ndeloof]

Sure. A fix is proposed by @jhrotko here : #667

[idsulik]

Great!

[jhrotko]

there are more issues than in #667

[ndeloof]

indeed. I've been investigating docker/compose#12001 and can't find a simple fix.
I suggest we revert this and introduce test cases to cover the identified issues, so that next attempt (would be 3rd one 😓) to implement "interpolate after merge" would be safer.