git problems: >78 column commit message created by git revert. I'm stuck. What do I do?

[Alan Mackenzie]

Hello, Emacs.

Yet another git problem.

I did git revert -e <hash-1> <hash-2>, committing the results to my
local git repository.

I then did git pull --rebase.  This failed with the message "Line longer
than 78 characters in commit message".  The revert operation created log
messages with very long lines.  :-(

Then, following the suggestion in the error message, I did git rebase
--abort, to get back to a stable state.

However, I now have two unrebaseable commits in my repo, and it seems
likely the savannah server would reject them anyway.

I'd like to use git commit --amend, but this can only change one of the
two commit messages created by git revert.

How can I resolve this mess?

-- 
Alan Mackenzie (Nuremberg, Germany).