logger.lifecycle("Performing checkout of {}...", refspec);
                LoggedExec.exec(execOperations, spec -> {
                    spec.workingDir(checkoutDir);
                    spec.commandLine("git", "checkout", effectiveRefSpec);
                });

                String checkoutHash = GitInfo.gitInfo(checkoutDir).getRevision();

	}
	pos := src.MakePos(in.Base(), uint(in.Line())+1, 1) // +1 because #line nnn means line nnn starts on next line
	in.Stack.SetBase(src.NewLinePragmaBase(pos, file, objabi.AbsFile(objabi.WorkingDir(), file, *flags.TrimPath), uint(line), 1))
}

// #undef processing
func (in *Input) undef() {
	name := in.macroName()
	if in.macros[name] == nil {
		in.Error("#undef for undefined macro:", name)
	}