master: delete head repository checkout on exit

artiq/frontend/artiq_master.py

@@ -74,6 +74,7 @@ def main():
     else:
         repo_backend = FilesystemBackend(args.repository)
     repository = Repository(repo_backend, log.log)
+    atexit.register(repository.close)
     repository.scan_async()
 
     worker_handlers = {

artiq/master/repository.py

@@ -63,6 +63,10 @@ class Repository:
 
         self._scanning = False
 
+    def close(self):
+        # The object cannot be used anymore after calling this method.
+        self.backend.release_rev(self.head_rev)
+
     @asyncio.coroutine
     def scan(self):
         if self._scanning: