Bug#911558: balsa: Balsa can’t read some HTML mails

[G. Milde]

Package: balsa
Version: 2.5.6-2
Followup-For: Bug #911558

Additional info:

After updating to Buster, Balsa does no longer show HTML parts of mails.

If the mail is mulitpart, text+mail, the text is visible.
If the mail is just HTML, there is no text in the main window.

Workaround: The text is visible in the editor window, when clicking "reply".

-- System Information:
Debian Release: 10.1
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.19.0-6-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.utf8, LC_CTYPE=de_DE.utf8 (charmap=UTF-8), LANGUAGE=de_DE.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages balsa depends on:
ii  libc6                           2.28-10
ii  libcairo2                       1.16.0-4
ii  libcanberra-gtk3-0              0.30-7
ii  libcanberra0                    0.30-7
ii  libcompfaceg1                   1:1.5.2-5+b2
ii  libgdk-pixbuf2.0-0              2.38.1+dfsg-1
ii  libglib2.0-0                    2.58.3-2+deb10u1
ii  libgmime-2.6-0                  2.6.23+dfsg1-4
ii  libgnutls30                     3.6.7-4
ii  libgpgme11                      1.12.0-6
ii  libgspell-1-1                   1.6.1-2
ii  libgssapi-krb5-2                1.17-3
ii  libgtk-3-0                      3.24.5-1
ii  libgtksourceview-3.0-1          3.24.9-2
ii  libldap-2.4-2                   2.4.47+dfsg-3+deb10u1
ii  libnotify4                      0.7.7-4
ii  libpango-1.0-0                  1.42.4-7~deb10u1
ii  libpangocairo-1.0-0             1.42.4-7~deb10u1
ii  libsecret-1-0                   0.18.7-1
ii  libsqlite3-0                    3.27.2-3
ii  libssl1.1                       1.1.1d-0+deb10u2
ii  libwebkit2gtk-4.0-37            2.24.3-1~deb10u1
ii  libxml2                         2.9.4+dfsg1-7+b3
ii  pinentry-gnome3 [pinentry-x11]  1.1.0-2
ii  zlib1g                          1:1.2.11.dfsg-1

Versions of packages balsa recommends:
ii  ca-certificates    20190110
ii  gpgsm              2.2.12-1+deb10u1
ii  python3-html2text  2018.1.9-1
ii  yelp               3.31.90-1