*: fix typos which duplicate a word

Fix typos in documentation, code comments, and RelNotes which repeat
various words.  In trivial cases, just delete the duplicated word and
rewrap text, if needed.  Reword the affected sentence in
Documentation/RelNotes/1.8.4.txt for it to make sense.

Signed-off-by: Andrei Rybak <rybak.a.v@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/log.c

@@ -1968,8 +1968,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	} else if (rev.diffopt.close_file) {
 		/*
 		 * The diff code parsed --output; it has already opened the
-		 * file, but but we must instruct it not to close after each
-		 * diff.
+		 * file, but we must instruct it not to close after each diff.
 		 */
 		rev.diffopt.no_free = 1;
 	} else {