skip test_crash_before_compact test for RemoteRepository

it was silently failing until recently. and it can't work the way it is on RemoteRepository.
it's still active (and now even really working) for the (local) Repository tests.

borg/testsuite/repository.py

@@ -328,3 +328,7 @@ class RemoteRepositoryCheckTestCase(RepositoryCheckTestCase):
 
     def open(self, create=False):
         return RemoteRepository(Location('__testsuite__:' + os.path.join(self.tmppath, 'repository')), create=create)
+
+    def test_crash_before_compact(self):
+        # skip this test, we can't mock-patch a Repository class in another process!
+        pass