revision: disallow reflog walking with revs->limited

The reflog-walk code doesn't work with limit_list(). That function traverses down the real history graph, not the fake reflog history that get_revision() returns. So it's not going to actually examine all of the commits we're going to show, because we'd add them to the pending list only during the actual traversal. In practice this limitation doesn't really matter, because the options that require list-limiting generally need UNINTERESTING endpoints or symmetric ranges, which already are forbidden for reflog walks. Still, there are likely some corner cases that would behave oddly. We're better off to warn the user that we can't fulfill their request than to generate potentially wrong output. This will also make it easier to refactor the reflog-walking code, because it eliminates a whole area of corner cases we'd have to consider (that already don't work anyway). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>