Merge branch 'jc/pickaxe' into next

* jc/pickaxe:
  git-pickaxe: optimize by avoiding repeated read_sha1_file().
  git-blame: add internal statistics to count read blobs.
  git-pickaxe: fix origin refcounting
  git-pickaxe: re-scan the blob after making progress with -C
  git-pickaxe: re-scan the blob after making progress with -M
  git-pickaxe: simplify Octopus merges further
  git-pickaxe: rename detection optimization

diff.h

@@ -46,6 +46,7 @@ struct diff_options {
 	const char *filter;
 	const char *orderfile;
 	const char *pickaxe;
+	const char *single_follow;
 	unsigned recursive:1,
 		 tree_in_recursive:1,
 		 binary:1,