'git merge --abort' is equivalent to 'git reset --merge' when
`MERGE_HEAD` is present.
+--allow-unrelated-histories::
+ By default, `git merge` command refuses to merge histories
+ that do not share a common ancestor. This option can be
+ used to override this safety when merging histories of two
+ projects that started their lives independently. As that is
+ a very rare occasion, no configuration variable to enable
+ this by default exists and will not be added, and the list
+ of options at the top of this documentation does not mention
+ this option. Also `git pull` does not pass this option down
+ to `git merge` (instead, you `git fetch` first, examine what
+ you will be merging and then `git merge` locally with this
+ option).
+
<commit>...::
Commits, usually other branch heads, to merge into our branch.
Specifying more than one commit will create a merge with