the parents have only two variants and the merge result picks
one of them without modification.
+--combined-all-paths::
+ This flag causes combined diffs (used for merge commits) to
+ list the name of the file from all parents. It thus only has
+ effect when -c or --cc are specified, and is likely only
+ useful if filename changes are detected (i.e. when either
+ rename or copy detection have been requested).
+
-m::
This flag makes the merge commits show the full diff like
regular commits; for each merge parent, a separate log entry