Can I force a "no-changes rebase" without a rerere history DB?
<sub>(a variation on on @j6t 's suggestion:)</sub>
You can use the commit editing feature of [`git-filter-repo`][1]. This tool is generally interesting for applying callback-based or analysis-based transformations on git repositories, but the specific capability you would likely use is the ability to run a given Python script on each commit:
```
$ cd /path/to/repository
$ git-filter-repo --commit-callback 'SCRIPT BODY HERE'
```
Now, when the script is run, an object named `commit` will be defined. This object has, among others, the fields `commit.original_id` holding the hash, and `commit.message` holding the commit message. Thus your script might be something like:
```
'if (commit.hash.startswith(b"0xdeadbeaf")):
commit.message.replace(b"Hello world", b"Goodbye world")
'
```
You can also look at [a few more examples][2] of git-filter-repo scripts.
Caveat: Haven't tried this myself yet.
[1]: https://github.com/newren/git-filter-repo
[2]: https://htmlpreview.github.io/?https://github.com/newren/git-filter-repo/blob/docs/html/git-filter-repo.html#EXAMPLES
