L2SS-176: Add git version utility to our device docker containers

devices/util/lofar2_git.py

+import git # pip3 install gitpython
+import os
+
+def get_repo(starting_directory: str = ".") -> git.Repo:
+    """ Try finding the repository by traversing up the tree. """
+
+    directory = starting_directory
+
+    try:
+        return git.Repo(directory)
+    except git.InvalidGitRepositoryError:
+        pass
+
+    # We now have to traverse up the tree
+    while directory != "/" and os.path.exists(directory):
+        # Go to parent
+        directory = os.path.abspath(directory + os.path.sep + "..")
+
+        try:
+            return git.Repo(directory)
+        except git.InvalidGitRepositoryError:
+            pass
+
+    raise git.InvalidGitRepositoryError("Could not find git repository root in {}".format(starting_directory))
+
+
+def get_version(repo: git.Repo = None) -> str:
+    """ Return a version string for the current commit. """
+
+    if repo is None:
+        repo = get_repo()
+
+    return "{} [{}{}]".format(repo.active_branch, repo.commit(), " (dirty)" if repo.is_dirty() else "")