Fix hg clone race with writer Most read operations in hg don't need locks because we order reads and writes for consistency. Clone is an exception to this as we're copying entire file histories and could end up with more file history copied than we have commits. For now, make clone take a lock on the source repo. Non-hardlinked clone should eventually be changed to use lockless pull.

def demandload(scope, modules):
    class d:
        def __getattr__(self, name):
            mod = self.__dict__["mod"]
            scope = self.__dict__["scope"]
            scope[mod] = __import__(mod, scope, scope, [])
            return getattr(scope[mod], name)

    for m in modules.split():
        dl = d()
        dl.mod = m
        dl.scope = scope
        scope[m] = dl