simplify previous patch-set by special casing 2-line staves

input/regression/repeat-sign-global-size-10.ly

Index: input/regression/repeat-sign-global-size-10.ly
diff --git a/input/regression/repeat-sign-global-size-10.ly b/input/regression/repeat-sign-global-size-10.ly
index 130a37f88a7b820d7d8df4f7eb265fcbf21ba9f3..3fea78a4a8b080a3034e5ca2f78522a19ce730cb 100644
--- a/input/regression/repeat-sign-global-size-10.ly
+++ b/input/regression/repeat-sign-global-size-10.ly
@@ -10,31 +10,39 @@ Test set-global-staff size 10 (with layout-set-staff-size)."
 \score {
   <<
     \context Staff = "s1" \with {
-      \override StaffSymbol #'line-positions = #'(-4 -2 0 2)
-      \override StaffSymbol #'staff-space = #0.7
+      \override StaffSymbol #'staff-space = #0.6
     } {
       s1 \bar ":|"
     }
 
     \context Staff = "s2" \with {
-      \override StaffSymbol #'staff-space = #0.6
+      \override StaffSymbol #'line-positions = #'(-4 -2 0 2)
+      \override StaffSymbol #'staff-space = #0.7
     } {
       s1 \bar ":|"
     }
+
+    \context Staff = "s3" {
+      s1 \bar ":|"
+    }
   >>
 }
 
 \score {
   <<
-    \context Staff = "s1" \with {
-      \override StaffSymbol #'staff-space = #1.6
-    } {
+    \context Staff = "s1" {
       s1 \bar ":|"
     }
 
     \context Staff = "s2" \with {
       \override StaffSymbol #'staff-space = #1.7
-      \override StaffSymbol #'line-count = #4
+      \override StaffSymbol #'line-positions = #'(-4 -2 0 2)
+    } {
+      s1 \bar ":|"
+    }
+
+    \context Staff = "s3" \with {
+      \override StaffSymbol #'staff-space = #3
     } {
       s1 \bar ":|"
     }