one of the parents is TREESAME, we follow only that one, so the other
sides of the merge are never walked.
+Finally, there is a fourth simplification mode available:
+
+--simplify-merges::
+
+ First, build a history graph in the same way that
+ '\--full-history' with parent rewriting does (see above).
++
+Then simplify each commit `C` to its replacement `C'` in the final
+history according to the following rules:
++
+--
+* Set `C'` to `C`.
++
+* Replace each parent `P` of `C'` with its simplification `P'`. In
+ the process, drop parents that are ancestors of other parents, and
+ remove duplicates.
++
+* If after this parent rewriting, `C'` is a root or merge commit (has
+ zero or >1 parents), a boundary commit, or !TREESAME, it remains.
+ Otherwise, it is replaced with its only parent.
+--
++
+The effect of this is best shown by way of comparing to
+'\--full-history' with parent rewriting. The example turns into:
++
+-----------------------------------------------------------------------
+ .-A---M---N---O
+ / / /
+ I B D
+ \ / /
+ `---------'
+-----------------------------------------------------------------------
++
+Note the major differences in `N` and `P` over '\--full-history':
++
+--
+* `N`'s parent list had `I` removed, because it is an ancestor of the
+ other parent `M`. Still, `N` remained because it is !TREESAME.
++
+* `P`'s parent list similarly had `I` removed. `P` was then
+ removed completely, because it had one parent and is TREESAME.
+--
ifdef::git-rev-list[]
Bisection Helpers