Ignore t3.py as well

I use like to use test/tests/t.py and t2.py as temporary test files,
so that they can get hooked into the makefile helpers, but the tester
ignores them.  Do this for t3.py too.

.gitignore

@@ -32,6 +32,7 @@ pystontmp*/
 *.cache
 tests/t.py
 tests/t2.py
+tests/t3.py
 *.bc
 stdlib.ll
 *.o

tools/tester.py

@@ -518,7 +518,7 @@ def main(orig_dir):
     patterns = opts.pattern
 
     if not patterns and not TESTS_TO_SKIP:
-        TESTS_TO_SKIP = ["t", "t2"]
+        TESTS_TO_SKIP = ["t", "t2", "t3"]
 
     assert os.path.isdir(TEST_DIR), "%s doesn't look like a directory with tests in it" % TEST_DIR