[XeTeX] Incorrect rendering of Vedic Sanskrit accents

[David M. Jones]

I posted this to the XeTeX sourceforge tracker a couple of weeks ago,
and it was suggested that I also mention it here.  The sourceforge
ticket is

    https://sourceforge.net/p/xetex/bugs/111/

and the zip file is

    https://sourceforge.net/p/xetex/bugs/111/attachment/xetex-indic-bug.zip

Cheers,
David.

P.S. There's actually a third class of bug that is clearly visible in
the table at the top of my document, but which I didn't mention
explicitly: XeTeX won't typeset one of the Devanagari combining
characters in isolation without adding a prothetic dotted circle
(U+25CC).

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On a lark, I've been experimenting with typesetting Vedic Sanskrit,
specifically verses from the Ṛg-Veda, using the Murty Hindi font from
Tiro Typeworks.  So far, XeTeX works beautifully, with two exceptions
involving the Vedic udatta and anudatta accent marks:

a) They don't attach properly to the Devanagari digits 1 and 3, and

b) They don't combine properly with the candrabindu, anusvara, and
   visarga signs.

luaTeX does render these correctly, so it doesn't appear to be a
problem with the font itself.

I've included a zip file with a test file and sample output from
luaTeX and XeTeX.

Is this a bug, or am I missing something obvious?