TortoiseGit amend merge commit: "show diff to last commit" checkbox is disabled

Question

I'm trying to commit --amend to a merge commit with TortoiseGit 2.13.0.1.

For a repository where the last commit is a merge commit, the "show diff to last commit" checkbox is disabled (greyed) and checked after i check the amend checkbox; it doesn't let me uncheck it:

With other repositories, the checkbox isn't disabled and not checked automatically after i check the amend checkbox.

Is this per design or is there some hidden setting to enable the checkbox for this situation?

Answer 1

Seems like this is per design in TortoiseGit and there's no way to enable the checkbox with builtin functionality. I don't know if it always have been this way; i couldn't find much "amend" mentioned in the docs or the releasenotes.

There are two options i can see:

1. use another tool which doesn't have this restriction
2. use zDump to enable the checkbox at runtime