merge_sort to return relative revnos

[Wouter van Heyst]

For bug 4663 revnos need to be stamped on revisions that are not in the revision-history of the branch, when showing the log of the graph as it would be with a merged revision as the tip.

To do this I need to know the amount of revisions at merge_depth 0, requiring an extra pass during _show_log.

However, Robert mentioned that merge_sort could produce the needed revnos with little overhead.

[John A Meinel (jameinel)]

Larstiq, are you still waiting for this? For now, I'm marking it wishlist. We can bump it up to 0.9 and medium if you decide it is blocking something else.

[John A Meinel (jameinel)]

As of 0.12 merge_sort can return dotted revnos, which fit this need nicely.