tests: handle .t files without trailing LF
9a2de8dae27b made this simple test-test.t succeed silently:
$ printf ' $ true' > test-test.t
but did not give a usable .err in this case:
$ printf ' $ false' > test-test.t
The missing LF will now be fixed in the test output and it will thus give a
test failure and a solution in the .err file.
[ original upstream message ]