Use synthesized git repository data for testing

[nphilipp]

Story

As an rpmautospec contributor,
I want an easy way to synthesize git repositories as test data,
so I don’t have to deal with the tarballed dummy-test-package-gloster.

Acceptance Criteria

• Instead of using a “frozen” git repository, contributors can specify a git history declaratively.
• Existing tests are modified to synthesize their test data.
• The dummy-test-package-gloster-git.tar.gz tarball is removed.

Background

Historically, it was always awkward to modify the tests which work on a git repository, e.g. any changes there required changes in existing tests. David Kirwan started work on a generator which fills a repo with synthesized changes from a descriptive structure (e.g. a YAML file), this could be used as a starting point.