Fix Issue 12996 - SList: linearRemove cannot remove root node

[sigod]

auto s = SList!int(1, 2, 3, 4, 5);
auto r = s[];
auto r1 = s.linearRemove(r); // exception
auto r1 = s.linearRemove(r.take(5)); // this works

https://issues.dlang.org/show_bug.cgi?id=12996

[monarchdodra]

Ideally, this kind of special casing could be avoided if SList carried an empty root node, rather than simply having a root "pointer". But, this is as good a fix as any.

Approved for auto-testers.

[monarchdodra]

Auto-merge toggled on

[sigod]

Ideally, this kind of special casing could be avoided if SList carried an empty root node, rather than simply having a root "pointer".

I'll look at it when 2.066 will be available.