Outside staff dotted rests (v2.20 & 2.21)

[Pierre Perol-Schneider]

Hi BugSquad,
Dots from dotted rests are still moving vertically when placed outside the
staff; same with v2.21 but with a slightly different placement:

\version "2.20.0"
%\version "2.21.1"

\layout {
  indent = 0
  \cadenzaOn
  \context {
    \Staff
    \omit Clef
    \omit TimeSignature
  }
}

\relative {
  s8.
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  \bar "" \break
  s4.
  c,,,,\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  \bar "" \break
  s2.
  c,,,,\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  \bar "" \break
  s1.
  c,,,,\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
  c\rest d\rest e\rest f\rest g\rest a\rest b\rest
}

Cheers,
Pierre