Merge branch 'jn/branch-move-to-self'

* jn/branch-move-to-self:
  Allow checkout -B <current-branch> to update the current branch
  branch: allow a no-op "branch -M <current-branch> HEAD"

branch.h

@@ -13,7 +13,8 @@
  * branch for (if any).
  */
 void create_branch(const char *head, const char *name, const char *start_name,
-		   int force, int reflog, enum branch_track track);
+		   int force, int reflog,
+		   int clobber_head, enum branch_track track);
 
 /*
  * Validates that the requested branch may be created, returning the