Our clones must be without working directories

If we fully clone a repository (without --noupdate) it will create lots of
files and directories, that hgweb will scan continuously, looking for
repositories to serve.

mercurial-mirror/check_repo.py

@@ -27,7 +27,7 @@ def main():
             processes.append(run(['pull', '-R', repo_path]))
         else:
             print("Cloning missing repository %s from %s" % (name, url))
-            processes.append(run(['clone', url, repo_path]))
+            processes.append(run(['clone', '--noupdate', url, repo_path]))
 
     for process in processes:
         if process is not None: