Что сработало для меня, так это переустановить зависимость. Это тот случай, когда установленная версия более поздняя, чем последняя (какие синаптические шоу). Это действительно эквивалентно тому, чтобы позволить синаптическому понизить пакет зависимостей.
Другое дело, что это «aptitude»:
root@arau:~# aptitude install libgfortran3
The following NEW packages will be installed:
libgfortran3{b}
0 packages upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 250 kB of archives. After unpacking 1 230 kB will be used.
The following packages have unmet dependencies:
libgfortran3 : Depends: gcc-4.8-base (= 4.8.2-19ubuntu1) but 4.8.4-2ubuntu1~14.04 is installed.
Internal error: found 2 (choice -> promotion) mappings for a single choice.
The following actions will resolve these dependencies:
Keep the following packages at their current version:
1) libgfortran3 [Not Installed]
Accept this solution? [Y/n/q/?] n
Internal error: found 2 (choice -> promotion) mappings for a single choice.
Internal error: found 2 (choice -> promotion) mappings for a single choice.
The following actions will resolve these dependencies:
Downgrade the following packages:
1) cpp-4.8 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
2) gcc-4.8 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
3) gcc-4.8-base [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
4) libasan0 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
5) libatomic1 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
6) libgcc-4.8-dev [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
7) libgomp1 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
8) libitm1 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
9) libquadmath0 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
10) libstdc++6 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
11) libtsan0 [4.8.4-2ubuntu1~14.04 (now) -> 4.8.2-19ubuntu1 (trusty)]
Accept this solution? [Y/n/q/?] y