input/regression/scheme-text-spanner.ly: fix problem with constants (issue 11614044)

[david . nalesnik]

Reviewers: ,

Message:
Please review.

Thanks,
David

Description:
input/regression/scheme-text-spanner.ly: fix problem with constants

The file `input/regression/scheme-text-spanner.ly' assigns a constant
pair to the variable `event-drul' and subsequently attempts to modify
the pair.  This can lead to scheme-text-spanners not appearing when
requested in simultaneous contexts.  This patch fixes the problem.

Please review this at https://codereview.appspot.com/11614044/

Affected files:
  M input/regression/scheme-text-spanner.ly


Index: input/regression/scheme-text-spanner.ly
diff --git a/input/regression/scheme-text-spanner.ly  
b/input/regression/scheme-text-spanner.ly
index  
309fdd6926cbe9a0463f88b9646fa0528aa3a8fe..917ee8b09a23b2b1b6f01487ff78aedf0529d689  
100644
--- a/input/regression/scheme-text-spanner.ly
+++ b/input/regression/scheme-text-spanner.ly
@@ -114,7 +114,7 @@ schemeTextSpannerEngraver =
    (let ((span '())
          (finished '())
          (current-event '())
-         (event-drul '(() . ())))
+         (event-drul (cons '() '())))
      (make-engraver
       (listeners ((scheme-text-span-event engraver event)
                  (if (= START (ly:event-property event 'span-direction))
@@ -154,7 +154,7 @@ schemeTextSpannerEngraver =
                 (set! (ly:spanner-bound finished RIGHT)
                       (ly:context-property context 'currentMusicalColumn)))
             (set! finished '())
-            (set! event-drul '(() . ())))))
+            (set! event-drul (cons '() '())))))
       ((finalize trans)
        (if (ly:spanner? finished)
           (begin