If provided, this will be called with the commit content, allowing
a signature to be added to the rebase commit. Can be skipped with
git_error_code.GIT_PASSTHROUGH. If git_error_code.GIT_PASSTHROUGH is returned, a commit will be made
without a signature.
This field is only used when performing git_rebase_commit.
If provided, this will be called with the commit content, allowing a signature to be added to the rebase commit. Can be skipped with git_error_code.GIT_PASSTHROUGH. If git_error_code.GIT_PASSTHROUGH is returned, a commit will be made without a signature. This field is only used when performing git_rebase_commit.