revwalk: update the description for the default sorting

It changed from implementation-defined to git's default sorting, as there are
systems (e.g. rebase) which depend on this order. Also specify more explicitly
how you can get git's "date-order".

include/git2/revwalk.h

@@ -25,17 +25,15 @@ GIT_BEGIN_DECL
  */
 typedef enum {
 	/**
-	 * Sort the repository contents in no particular ordering;
-	 * this sorting is arbitrary, implementation-specific
-	 * and subject to change at any time.
+	 * Sort the output with the same default time-order method from git.
 	 * This is the default sorting for new walkers.
 	 */
 	GIT_SORT_NONE = 0,
 
 	/**
-	 * Sort the repository contents in topological order
-	 * (parents before children); this sorting mode
-	 * can be combined with time sorting.
+	 * Sort the repository contents in topological order (parents before
+	 * children); this sorting mode can be combined with time sorting to
+	 * produce git's "time-order".
 	 */
 	GIT_SORT_TOPOLOGICAL = 1 << 0,
 

src/revwalk.c

@@ -555,10 +555,6 @@ static int prepare_walk(git_revwalk *walk)
 		}
 	}
 
-	for (list = commits; list; list = list->next) {
-		printf("%s: commit %s\n", __func__, git_oid_tostr_s(&list->item->oid));
-	}
-
 	if ((error = limit_list(&commits, walk, commits)) < 0)
 		return error;