Merge branch 'maint-1.6.4' into maint

* maint-1.6.4:
  rebase -i: more graceful handling of invalid commands
  help -i: properly error out if no info viewer can be found

Author: gitster

builtin-help.c

@@ -372,6 +372,7 @@ static void show_info_page(const char *git_cmd)
 	const char *page = cmd_to_page(git_cmd);
 	setenv("INFOPATH", system_path(GIT_INFO_PATH), 1);
 	execlp("info", "info", "gitman", page, NULL);
+	die("no info viewer handled the request");
 }
 
 static void get_html_page_path(struct strbuf *page_path, const char *page)

git-rebase--interactive.sh

@@ -408,7 +408,12 @@ do_next () {
 		;;
 	*)
 		warn "Unknown command: $command $sha1 $rest"
-		die_with_patch $sha1 "Please fix this in the file $TODO."
+		if git rev-parse --verify -q "$sha1" >/dev/null
+		then
+			die_with_patch $sha1 "Please fix this in the file $TODO."
+		else
+			die "Please fix this in the file $TODO."
+		fi
 		;;
 	esac
 	test -s "$TODO" && return