bug#17874: 24.3.92; Incorrectly isolated ع in علی

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 29 Jun 2014 13:30:36 +0100
> From: penthief <penthief@SDF.ORG>
> 
> The following should display differently, as in 24.3.1.
> A.  ع ل ی - these are the "isolated" types.
> B.  علی  - this is a final, medial and initial type.
> C.  عل ی‎ - the isolated ی should be joined when the space is removed. 
> This is the bug demonstrated.
> 
> 0. Start emacs: $ emacs -Q
> 1. Output علی with a bold face in the appropriate font:
> (progn
>    (setq buffer-face-mode-face '(:family  "DejaVu Sans Mono" 
> :alternate-families  "Monaco" :height 100))
>    (buffer-face-mode)
>    (buffer-face-set 'bold)
>    (newline)
>    (insert " علی"))
> 
>   علی
> 
> 2. Change to a regular face:
> (buffer-face-set 'default)
>   علی
> 
> What happens is ی (ARABIC LETTER FARSI YEH) switches from the final to 
> the isolated type.

I cannot reproduce this on MS-Windows.  It works for me correctly both
in Emacs 24.3 and in the emacs-24 branch as of r117323.  Could be
libotf-specific.  Are you sure nothing changed in libotf and/or
m17n-flt libraries between the time you built v24.3 and now?