+ When in branch <name>, it tells `git fetch` the default refspec to
+ be marked for merging in FETCH_HEAD. The value has exactly to match
+ a remote part of one of the refspecs which are fetched from the remote
+ given by "branch.<name>.remote".
+ The merge information is used by `git pull` (which at first calls
+ `git fetch`) to lookup the default branch for merging. Without
+ this option, `git pull` defaults to merge the first refspec fetched.
+ Specify multiple values to get an octopus merge.