Use of mode="assign" in default configuration

Correcting the above bug may introduce this issue:
https://bugs.freedesktop.org/show_bug.cgi?id=60748
that has been fixed by using target="pattern" instead of target="font".

For example, the 10-antialias.conf file at the moment is:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!-- Use the Antialiasing -->
  <match target="font">
    <edit name="antialias" mode="assign"><bool>true</bool></edit>
  </match>
</fontconfig>

it should become:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!-- Use the Antialiasing -->
  <match target="pattern">
    <edit name="antialias" mode="append">
      <bool>true</bool>
    </edit>
  </match>
</fontconfig>

Thank you for taking the time to report this bug! This bug will be fixed in Ubuntu 18.04 LTS.

This bug was fixed in the package fontconfig - 2.12.6-0ubuntu1

---------------
fontconfig (2.12.6-0ubuntu1) bionic; urgency=medium

  * Merge with Debian (LP: #1638959, LP: #1702544). Remaining changes:
    - debian/source_fontconfig.py, debian/fontconfig.install:
      + Install apport hook
    - Add 03_prefer_dejavu.patch:
      + Prefer DejaVu to Bitstream Vera
    - Add 04_ubuntu_monospace_lcd_filter_conf.patch:
      + Use legacy lcdfilter with smaller monospace fonts
    - Add 05_ubuntu_add_antialiasing_confs.patch:
      + Add config file for antialiasing
    - Add 05_lcdfilterlegacy.patch: Recognize const value "lcdfilterlegacy",
      used in Ubuntu before upstream introduced "lcdlegacy"
    - Add 07_no_bitmaps.patch:
      + Install 70-no-bitmaps.conf
    - Drop debian/fontconfig.NEWS, debian/fontconfig-config.templates,
      debian/fontconfig-config.config, and associatedpo files.
      Modify debian/rules, debian/fontconfig-config.postinst,
      debian/fontconfig-config.postrm, and debian/README.Debian.
      + Don't provide debconf prompts
    - Modify debian/rules, debian/fontconfig-config.install,
      debian/fontconfig-config.links, debian/fontconfig-config.postrm,
      and debian/fontconfig-udeb.install:
      + Delay doing the transition from /etc to /usr
  * New upstream release
  * Refresh patches
  * Update Ubuntu patches to use mode="append" and target="pattern"
    (LP: #1192175)
  * Drop patches applied in new release:
    - 01_fonts_nanum.patch
    - 03_locale_c.utf8.patch
    - 06_cross.patch
    - CVE-2016-5384.patch

fontconfig (2.12.3-1) unstable; urgency=low

  * Rebuild current bits as maintainer upload
  * Add dependency on python2.7, python-lxml, python-six
  * Add dependency on docbook, docbook-utils, texlive-formats-extra
  * Set FREETYPE_PROPERTIES=truetype:interpreter-version=35 iff
    selected hintstyle is hintfull. This produces fully hinted glyphs
    with current FreeType bits.

fontconfig (2.12.3-0.2) unstable; urgency=medium

  * Non-maintainer upload.
  * Add a NEWS file to describe the change in the default hinting style. Also
    add a debconf question to allow the administrator to change it (Closes:
    #866950)

fontconfig (2.12.3-0.1) unstable; urgency=medium

  * Non-maintainer upload.
  * New upstream release
    - Do not FTBFS if docbook-utils is installed (Closes: #862483)
    - Drop debian/patches/01_path_max.patch, merged upstream
    - Refresh debian/patches/06_cross.patch
  * debian/watch: Switch to .bz2 tarballs
  * debian/control: Bump Standards-Version to 4.0.0 (no further changes)

fontconfig (2.12.1-0.1) experimental; urgency=medium

  * Non-maintainer upload.
  * New upstream release (Closes: #816045)
    - d/p/01_path_max.patch, d/p/06_cross.patch: Refreshed
    - Drop patches/05_doc_files.patch, the tarball already contains the
      pre-generated documentation
    - Drop d/p/07_CVE-2016-5384-Properly-validate-offsets-in-cache-files.patch:
      Applied upstream
  * Drop -dbg package and rely on the -dbgsym ones, bump debhelper dependency
    to be sure that dh_stip has --dbgsym-migration flag
  * debian/rules: Pass --enable-static flag to also build the static library
  *...