bug#28420: enriched mode stores fg colors, but don't display them

[Mutiny]

since some days emacs displays foreground colors when selected, stores them, however don't display them after a re-open of the document. Attached the document and some technicalm info.
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./configure                             \
      --prefix=$deploy_folder              \
      --sysconfdir=$sysconfdir             \
      --enable-locallisppath=$locallisppath    \
      --libexecdir=$libexecdir              \
      --localstatedir=$localstatedir          \
      --enable-largefile                    \
      --with-x-toolkit=gtk3                 \
      --with-sound=yes                    \
      --with-modules                       \
      --with-xwidgets                      \
      --without-pop                       \
      --with-file-notification=yes             

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GNU Emacs 26.0.50 of 2017-09-11
dist:  Fedora release 26 (Twenty Six)
subdist: none.
kernel: Linux XXX 4.12.9-300.fc26.x86_64
----
Code:
Content-Type: text/enriched
Text-Width: 70

<x-color>-*- mode: enriched -*-
<x-color><param>blue</param>blue</x-color></x-color> <x-color><x-color><param>red</param>red</x-color></x-color> none