detector: use [] instead of false

Signed-off-by: Václav Valíček <valicek1994@gmail.com>

repo_cloner/lib/detector.py

@@ -173,7 +173,11 @@ class Detector:
 	def run(self, callback: Callable[[DetectedCommit], None]) -> int:
 		log.info(f"Running commit detector")
 		new_branches = self._repo.list_branches()
+		if not new_branches:
+			new_branches = []
 		new_tags = self._repo.list_tags()
+		if not new_tags:
+			new_tags = []
 
 		# remove removed
 		old_keys = self._branches.keys()