markup-command rounded-box is broken

[Thomas Morley]

Hi,

I noticed a bug with recent master:

\markup \rounded-box "foo"

prints completely black.

First bad commit is:
commit 0772e38398972d6c2b4ba9e6f42e7725d973e08b
Author: Han-Wen Nienhuys <hanwenn@gmail.com>
Date:   Sun Aug 1 11:15:02 2021 +0200

    Stop passing color names to output backends

I could fix it with the following diff

$ git diff
diff --git a/scm/stencil.scm b/scm/stencil.scm
index 0409242a05..35937f9d43 100644
--- a/scm/stencil.scm
+++ b/scm/stencil.scm
@@ -708,10 +708,10 @@ producing a new stencil."
                  (interval-widen xext ideal-thickness)
                  (interval-widen yext ideal-thickness)
                  ideal-blot))
-         (inner (ly:make-stencil (ly:stencil-in-color
-                                  (ly:round-filled-box
-                                   xext yext (- ideal-blot ideal-thickness))
-                                   "white"))))
+         (inner
+           (ly:stencil-in-color
+             (ly:round-filled-box xext yext (- ideal-blot ideal-thickness))
+             "white")))
     (set! stencil (ly:stencil-add outer inner))
     stencil))

i.e. commenting ly:make-stencil.
Alas I don't know why the former code worked at all, thus I hesitate
to upload a patch at those lines.

Any insights?

Cheers,
  Harm