UTC just decided to do an erratum that corrects the Joining_Type of two Mandaic letters. This should be fixed in HarfBuzz. Here's the document that will become a part of the erratum: http://www.unicode.org/L2/L2014/14194-mandaic-feedback.pdf Basically, U+0847 should become Right-joining and U+084F should become dual-joining.
commit d277c3d7eee1fd4fb41c38255e5c4df539353e89 Author: Behdad Esfahbod <behdad@behdad.org> Date: Thu Aug 7 15:38:52 2014 -0400 [arabic] Bug 82306 - Mandaic had errors in its Unicode Joining_Type Fixes https://bugs.freedesktop.org/show_bug.cgi?id=82306
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