vim-patch:8.1.1490: when a single test fails the exit code is not set

Problem:    When a single test fails the exit code is not set. (Daniel Hahler)
Solution:   Add an exit command. (closes vim/vim#4506)
4e0bf84627

src/nvim/testdir/Makefile

@@ -118,10 +118,10 @@ fixff:
 $(NEW_TESTS):
 	rm -f $@.res test.log messages
 	$(MAKE) -f Makefile $@.res
-	@if test -f test.log; then \
-		cat test.log; \
-	fi
 	cat messages
+	@if test -f test.log; then \
+		exit 1; \
+	fi
 
 RM_ON_RUN   := test.out X* viminfo
 RM_ON_START := test.ok