Fix various issues found in comments

A random hodge-podge of incorrect or out-of-date comments that I found:

  * t6423 had a comment that has referred to the wrong test for years;
    fix it to refer to the right one.
  * diffcore-rename had a FIXME comment meant to remind myself to
    investigate if I could make another code change.  I later
    investigated and removed the FIXME, but while cherry-picking the
    patch to submit upstream I missed the later update.  Remove the
    comment now.
  * merge-ort had the early part of a comment for a function; I had
    meant to include the more involved description when I updated the
    function.  Update the comment now.

Signed-off-by: Elijah Newren <newren@gmail.com>
Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-rename.c

@@ -1544,7 +1544,7 @@ void diffcore_rename_extended(struct diff_options *options,
 			/* all the usual ones need to be kept */
 			diff_q(&outq, p);
 		else
-			/* no need to keep unmodified pairs; FIXME: remove earlier? */
+			/* no need to keep unmodified pairs */
 			pair_to_free = p;
 
 		if (pair_to_free)

merge-ort.c

@@ -2533,7 +2533,7 @@ static int compare_pairs(const void *a_, const void *b_)
 	return strcmp(a->one->path, b->one->path);
 }
 
-/* Call diffcore_rename() to compute which files have changed on given side */
+/* Call diffcore_rename() to update deleted/added pairs into rename pairs */
 static void detect_regular_renames(struct merge_options *opt,
 				   unsigned side_index)
 {
@@ -2586,8 +2586,10 @@ static void detect_regular_renames(struct merge_options *opt,
 }
 
 /*
- * Get information of all renames which occurred in 'side_pairs', discarding
- * non-renames.
+ * Get information of all renames which occurred in 'side_pairs', making use
+ * of any implicit directory renames in side_dir_renames (also making use of
+ * implicit directory renames rename_exclusions as needed by
+ * check_for_directory_rename()).  Add all (updated) renames into result.
  */
 static int collect_renames(struct merge_options *opt,
 			   struct diff_queue_struct *result,

t/t6423-merge-rename-directories.sh

@@ -454,7 +454,7 @@ test_expect_success '1f: Split a directory into two other directories' '
 #   the directory renamed, but the files within it. (see 1b)
 #
 #   If renames split a directory into two or more others, the directory
-#   with the most renames, "wins" (see 1c).  However, see the testcases
+#   with the most renames, "wins" (see 1f).  However, see the testcases
 #   in section 2, plus testcases 3a and 4a.
 ###########################################################################