Issue 4664: Ensure one beam is left in subdivided beams

Issue #4355 introduced the concept that in subdivided beams the
division beam should reflect the length of the subsequent group.

However, with groups equal to or longer than one quarter note this
resulted in *no* beam left.

This commit ensures that at least one beam is returned when a beam is
active and subdivideBeam = ##t

1 files changed, 18 insertions, 0 deletions

diff --git a/input/regression/beam-subdivide-quarter-notes.ly b/input/regression/beam-subdivide-quarter-notes.ly
new file mode 100644
index 0000000000..af28282aca
--- /dev/null
+++ b/input/regression/beam-subdivide-quarter-notes.ly
@@ -0,0 +1,18 @@
+\version "2.19.32"
+
+\header {
+  
+  doctitle = "Beam subdivide over quarter notes"
+
+  texidoc = "Beam subdivisions should match the durations of the subdivided
+groups, as established by baseMoment.  However, if the groups are equal or
+longer than quarter notes, one beam should be left
+"
+
+}
+
+\relative c' {
+    \set baseMoment = #(ly:make-moment 1/4)
+    \set subdivideBeams = ##t
+    c16 [ c c c c c c c c c c c c c c c ]
+}