Product: Fedora https://bugzilla.redhat.com/show_bug.cgi?id=799565
--- Comment #21 from Behdad Esfahbod behdad@fedoraproject.org --- Testing with the font in comment 14, I see the reordering happening. Here's the hb-shape output:
$ ./hb-unicode-encode d4e,d15 | build/util/hb-shape ./Lohit-Malayalam.ttf --shaper ot [U0D15=0+1015|uni0D4E=0@-971,-41+0]