[PATCH 3/4] tests: notice valgrind error in test_must_fail

We tell valgrind to return 126 if it notices that something is wrong,
but we did not actually handle this in test_must_fail, leading to
false negatives.  Catch and report it.

Signed-off-by: Thomas Rast <redacted>
---

Just noticed this issue when tracking down the failure in t7612.  It
might still be a bit too fragile; when running the entire suite under
valgrind, I usually just

  cd test-results
  egrep '^==[0-9]+==' *.out| less -S


 t/test-lib-functions.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index fa62d01..6766553 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh

@@ -536,6 +536,9 @@ test_must_fail () {
 	elif test $exit_code = 127; then
 		echo >&2 "test_must_fail: command not found: $*"
 		return 1
+	elif test $exit_code = 126; then
+		echo >&2 "test_must_fail: valgrind error: $*"
+		return 1
 	fi
 	return 0
 }

-- 
1.8.2.467.gedf93a5