Fix `unstub` cleanup process for failed stubs

test/test_helper.bash

@@ -36,9 +36,12 @@ unstub() {
 
   export "${prefix}_STUB_END"=1
 
-  "$path"
+  local STATUS=0
+  "$path" || STATUS="$?"
+
   rm -f "$path"
   rm -f "${TMP}/${program}-stub-plan" "${TMP}/${program}-stub-run"
+  return "$STATUS"
 }
 
 install_fixture() {