t: fix some trivial cases of ignored exit codes in loops

These are all cases where we do a setup step of the form:

  for i in $foo; do
	  set_up $i || break
  done &&
  more_setup

would not notice a failure in set_up (because break always
returns a 0 exit code). These are just setup steps that we
do not expect to fail, but it does not hurt to be defensive.

Most can be fixed by converting the "break" to a "return 1"
(since we eval our tests inside a function for just this
purpose). A few of the loops are inside subshells, so we can
use just "exit 1" to break out of the subshell. And a few
can actually be made shorter by just unrolling the loop.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4024-diff-optimize-common.sh

@@ -139,7 +139,7 @@ test_expect_success setup '
 		( printf C; zs $n ) >file-c$n &&
 		( echo D; zs $n ) >file-d$n &&
 
-		expect_pattern $n || break
+		expect_pattern $n || return 1
 
 	done >expect
 '