[CBM] TestAssertDatasetExistsUnknownError always fails on MacOS

--- FAIL: TestAssertDatasetExistsUnknownError (0.00s)

    import_test.go:24:

                Error Trace:    /Users/mathall/Documents/code/cb_enterprise_src/backup/utils/import_test.go:24

                Error:          Not equal:

                                expected: "failed to check if dataset /root/to/file exists: stat /root/to/file: permission denied"

                                actual  : "dataset /root/to/file does not exist"

                                Diff:

                                --- Expected

                                +++ Actual

                                @@ -1 +1 @@

                                -failed to check if dataset /root/to/file exists: stat /root/to/file: permission denied

                                +dataset /root/to/file does not exist

                Test:           TestAssertDatasetExistsUnknownError