std.container: RedBlackTree.remove readability enhancement.

[Safety0ff]

Minor change to make the code easier to read.

[schveiguy]

Seems fine. Looking at your change, I wonder if y should just go away, and use ret instead.

[Safety0ff]

I don't think replacing y for ret is an improvement.
The section where y is used could almost directly be moved to a separate swapping function. e.g.:
// if this node has 2 children
if (_left !is null && _right !is null)
swap(this, ret); // stable: only swaps pointers
So its probably better to treat it as a separate subroutine for reading purposes.

[monarchdodra]

If possible, I'd like this to not be merged before #2174.

[Safety0ff]

ping, #2174 has been merged and I've rebased this.

[DmitryOlshansky]

Auto-merge toggled on