Merge branch 'es/test-chain-lint'

Broken &&-chains in the test scripts have been corrected.

* es/test-chain-lint:
  t6000-t9999: detect and signal failure within loop
  t5000-t5999: detect and signal failure within loop
  t4000-t4999: detect and signal failure within loop
  t0000-t3999: detect and signal failure within loop
  tests: simplify by dropping unnecessary `for` loops
  tests: apply modern idiom for exiting loop upon failure
  tests: apply modern idiom for signaling test failure
  tests: fix broken &&-chains in `{...}` groups
  tests: fix broken &&-chains in `$(...)` command substitutions
  tests: fix broken &&-chains in compound statements
  tests: use test_write_lines() to generate line-oriented output
  tests: simplify construction of large blocks of text
  t9107: use shell parameter expansion to avoid breaking &&-chain
  t6300: make `%(raw:size) --shell` test more robust
  t5516: drop unnecessary subshell and command invocation
  t4202: clarify intent by creating expected content less cleverly
  t1020: avoid aborting entire test script when one test fails
  t1010: fix unnoticed failure on Windows
  t/lib-pager: use sane_unset() to avoid breaking &&-chain

t/t4024-diff-optimize-common.sh

@@ -149,7 +149,7 @@ test_expect_success 'diff -U0' '
 
 	for n in $sample
 	do
-		git diff -U0 file-?$n
+		git diff -U0 file-?$n || return 1
 	done | zc >actual &&
 	test_cmp expect actual