Prevent --index-info from ignoring -z.

If git-update-index --index-info -z is used only the first
record given to the process will actually be updated as
the -z option is ignored until after all index records
have been read and processed.  This meant that multiple
null terminated records were seen as a single record which
was lacking a trailing LF, however since the first record
ended in a null the C string handling functions ignored the
trailing garbage.  So --index-info should be required to be
the last command line option, much as --stdin is required
to be the last command line option.  Because --index-info
implies --stdin this isn't an issue as the user shouldn't
be passing --stdin when also passing --index-info.
Signed-off-by: NShawn O. Pearce <spearce@spearce.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

update-index.c

@@ -577,9 +577,11 @@ int main(int argc, const char **argv)
 				break;
 			}
 			if (!strcmp(path, "--index-info")) {
+				if (i != argc - 1)
+					die("--index-info must be at the end");
 				allow_add = allow_replace = allow_remove = 1;
 				read_index_info(line_termination);
-				continue;
+				break;
 			}
 			if (!strcmp(path, "--ignore-missing")) {
 				not_new = 1;