Merge branch 'jl/read-tree-m-dry-run'

* jl/read-tree-m-dry-run:
  Teach read-tree the -n|--dry-run option
  unpack-trees: add the dry_run flag to unpack_trees_options

Documentation/git-read-tree.txt

@@ -53,6 +53,11 @@ OPTIONS
 	trees that are not directly related to the current
 	working tree status into a temporary index file.
 
+-n::
+--dry-run::
+	Check if the command would error out, without updating the index
+	nor the files in the working tree for real.
+
 -v::
 	Show the progress of checking files out.