Border anchors don't work inside groups

[LordBaryhobal]

When drawing a line between two circles, the endpoints are automatically chosen on the circles' perimeters.
However, if a circle is in a group and we try to draw a line from outside the group, it starts/ends at the center point.

For example:

#import "@preview/cetz:0.4.2": canvas, draw
#canvas({
  let ok = green + 2pt
  let nope = red + 2pt
  draw.circle((0, 0), name: "out1")
  draw.circle((4, 0), name: "out2")
  draw.line("out1", "out2", stroke: ok)  // outside to outside: OK

  draw.group(name: "grp", {
    draw.circle((0, -3), name: "in1")
    draw.circle((4, -3), name: "in2")

    draw.line("out1", "in2", stroke: ok)  // outside to inside (from inside): OK
    draw.line("in1", "in2", stroke: ok)  // inside to inside: OK
  })
  draw.line("out1", "grp.in1", stroke: nope)  // outside to inside (from outside): Nope
})

This also happens when drawing a line between two elements inside a group from without the group:

#canvas({
  draw.group(name: "grp", {
    draw.circle((0, 0), name: "a")
    draw.circle((4, 0), name: "b")
  })
  draw.line("grp.a", "grp.b")
})