fix: Repository should not be dirty with only untracked files

[jirkis]

Dirty repository status resolution used by git describe --dirty is that the repository is marked as dirty only when there are some 'local changes'.
git describe

Describe the state of the working tree. When the working tree matches HEAD, the output is the same as "git describe HEAD". If the working tree has local modification "-dirty" is appended to it. If a repository is corrupt and Git cannot determine if there is local modification, Git will error out, unless ‘--broken’ is given, which appends the suffix "-broken" instead.

If the repository contains only untracked files, git describe --dirty does not add the -dirty suffix, but this extension does, which is not correct.

[jirkis]

Any comments on this PR?