I found that adding the apt.conf option Aptitude::Always-Use-Safe-Resolver "true";
results in aptitude selecting the upgrade rather than the removal, but ONLY command-line aptitude. command-line obeys apt.conf, even disregarding the command-line "full-upgrade" invocation. On the other hand, TUI aptitude seems to have disregarded apt.conf; this may be related to bug #485832<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=485832> . I will continue to look for the root cause and a desirable solution. -- Chris Tillman Developer
