revpair: restrict odd-range handling to top-level x:y expression (issue4774) The odd-range hack was introduced by 2a0efa1112ac for backward compatibility, but it was too widely applied. I've checked cmdutil.revpair() at 1.6, and found that ".:", ":0" and ":" are also handled as pairs. So let's enable the hack only for "x:y", "x:", "y:" and ":". test-revset.t is updated because "tip^::tip^ or tip^" shouldn't be taken as an odd range. This patch adds "tip^:tip^" instead. This patch is written for the default branch because parse() of the stable branch lacks compatibility hack for "foo+bar" tag. If we want to mitigate the issue in stable, we can add something like "and '::' in revs[0]".