Add a doc string

mercurial/hg.py

@@ -49,6 +49,7 b' def islocal(repo):'
     return repo.local()
 
 def repository(ui, path=None, create=False):
+    """return a repository object for the specified path"""
     return _lookup(path).instance(ui, path, create)
 
 def defaultdest(source):