run-tests: fix -i when "#testcases" is used in .t test The "#testcases" feature introduced by 7340465bd788 has issues with "-i" because "-i" uses "test.name.endswith('.t')" to test if a test is .t or not. test.name could now be something like "test-foo.t (caseA)" so the above endswith test is no longer valid. This patch changes the test to use "self.path" which won't have the issue.