Prebase vowels not moved to before consonants joined by virama

[Richard Wordingham]

This bug was present in the implementation of USE up to Version 1.1.2 of HarfBuzz - https://github.com/behdad/harfbuzz/issues/180 records problem and fix in Version 1.1.3. The bug also affects the much-afflicted Tai Tham script, e.g. in the word ᩉ᩠ᩅᩯᩁ /wɛːn/ 'ring (n.)'. Unfortunately, LTS Ubuntu release 16.04 is still at Version 1.0.1 - there are no backports from Yakkety (Harfbuzz 1.2.7) or Zesty (Harfbuzz 1.4.2).

Potentially unsafe work-arounds include building HarfBuzz (e.g. Version 1.4.6) and replacing the sharable object libharfbuzz.so.0 with a user-generated sharable object.

It is possible to backport from Yakkety oneself using the Firefox example in "Recommended alternative to pinning" at https://help.ubuntu.com/community/PinningHowto. Note that the final command is

sudo apt-get -b source -t yakkety harfbuzz

One then installs the corrected object by means of the command

sudo dpkg -i libharfbuzz0b_1.2.7-1_i386.deb

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: libharfbuzz0b 1.0.1-1ubuntu0.1
ProcVersionSignature: Ubuntu 3.13.0-102.149-generic 3.13.11-ckt39
Uname: Linux 3.13.0-102-generic i686
ApportVersion: 2.20.1-0ubuntu2.9
Architecture: i386
CurrentDesktop: Unity
Date: Fri Jul 14 22:21:04 2017
InstallationDate: Installed on 2010-12-28 (2390 days ago)
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release i386 (20100816.1)
ProcEnviron:
 LANGUAGE=en_GB:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_GB.utf8
 SHELL=/bin/bash
SourcePackage: harfbuzz
UpgradeStatus: Upgraded to xenial on 2016-11-19 (237 days ago)