Merge branch 'maint'

* maint:
t4013: test diff-tree's --stdin commit formatting
diff-tree: avoid lookup_unknown_object
object_as_type: set commit index
alloc: factor out commit index
add object_as_type helper for casting objects
parse_object_buffer: do not set object type
move setting of object->type to alloc_* functions
alloc: write out allocator definitions
alloc.c: remove the alloc_raw_commit_node() function

diff --cc t/t4013-diff-various.sh
Simple merge