How to prevent a merge from reverting to a conventional merge strategy when merging with a fast transition is not possible?

Question

The git merge command has the ability to merge with fast forward, but this is not what I want, because if it cannot perform fast switching, it uses the usual merge.

Is there a git command that only performs fast merging (from a tracked remote branch) and does nothing if merging with a fast jump is not possible?

Answer 1

On the git-merge man page:

- and further only

Refuse to merge and exit with a non-zero status if the current HEAD is already updated or the merge can be enabled as fast forward.