Support commit message commands syntax

[devinrhode2]

I've been using this syntax when creating certain git commits, which are purely the result of running some command:

exec `npm install prettier --save-dev
exec `npm run prettier --write .`

When these commands cause merge conflicts, a tool could simply discard the original exec "..." commit, and re-run the command on top of the other change.

This could make rebase scripts like this irrelevant: https://stackoverflow.com/questions/71812872/how-to-rebase-when-prettier-formatting-was-applied-to-whole-project

[arxanas]

This is the intended use-case for git test fix; does that work for you?