Cursor.tick() inconsistent between different cursors

Hi all,

I'm running MuseScore 1.3 on 64-bit Win7 and I'm finding inconsistent results when calling tick() on two different Cursor objects that should be pointing to the exact same location. Specifically:

c1 = new Cursor(curScore, true);
c1.staff = 0;
c1.rewind();
c2 = new Cursor(curScore, true);
c2.staff = 0;
c2.rewind();

gives -1 when calling c1.tick() and 0 when calling c2.tick(). Curiously,

c1 = new Cursor(curScore);
c1.staff = 0;
c1.rewind();
c2 = new Cursor(curScore);
c2.staff = 0;
c2.rewind();

and

c1 = new Cursor(curScore, true);
c2 = new Cursor(curScore, true);
c1.staff = 0;
c2.staff = 0;
c1.rewind();
c2.rewind();

both give 0 for c1.tick() and c2.tick() as expected. Attached is a tiny JS plugin showing an instance of each example, which for me printed the results described above on both a single-measure test score and the Reunion example piece. Any insight on this issue would be appreciated.

Cheers,
Matthew