MH> Have you switched to dev and done a pull?
PS> your local dev branch is probably out of date. Try to checkout (switch to) dev first and do a `git pull` there. Then switch back to your standoff branch and do the merge.
PS> (There is also `git pull  -- all` but use with caution)
RV> I haven't used -m with git merge, so I'd be tempted to try 
RV> $ git merge dev
RV> And see if that makes a difference. It should prompt you to add a message (usually pregenerated for merges).
RV> You could also try to fetch before merging
RV> $ git fetch
RV> $ git merge dev

Thank you, gentlemen. Yes, I had failed to (properly) pull into dev.
BTW, I use the -m switch (which allows you to specify the commit message on the commandline) rather than rely on the default behavior because when git tries to prompt for the commit message from within Emacs it fails, kinda spectacularly. (All right, that may be an exaggeration, but certainly annoyingly.)