remoteloop: don't close a socket it didn't open

Closing the socket is the responsibility of whoever opened it.

Fix this in the only user (qemu assembler) by using socket() in a `with`
block, which closes the socket on exit.

assemblers/org.osbuild.qemu

@@ -111,8 +111,10 @@ def main(tree, output_dir, options, loop_client):
 
 if __name__ == '__main__':
     args = json.load(sys.stdin)
-    sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
-    sock.setsockopt(socket.SOL_SOCKET, socket.SO_PASSCRED, 1)
-    sock.connect("/run/osbuild/api/remoteloop")
-    ret = main(args["tree"], args["output_dir"], args["options"], remoteloop.LoopClient(sock))
+
+    with socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM) as sock:
+        sock.setsockopt(socket.SOL_SOCKET, socket.SO_PASSCRED, 1)
+        sock.connect("/run/osbuild/api/remoteloop")
+        ret = main(args["tree"], args["output_dir"], args["options"], remoteloop.LoopClient(sock))
+
     sys.exit(ret)

osbuild/remoteloop.py

@@ -112,9 +112,6 @@ class LoopClient:
     def __init__(self, sock):
         self.sock = sock
 
-    def __del__(self):
-        self.sock.close()
-
     def create_device(self, fd, dir_fd=None, offset=None, sizelimit=None):
         req = {}
         fds = array.array("i")