view debian/source/format @ 4992:1eab41625dee stable

evolve: abort if deciding resolution parent is ambiguous

While solving content-divergence, it could be hard to decide
which cset should be treated as a resolution parent if there
are multiple successors of divergent cset. i.e split case.

But we are planning to make some update in handling this split
case:
1) consider highest one if all splitted csets are in a single
topological branch
2) still need to decide if 1) doesn't apply

3.0 (quilt)