As seen in the log https://buildd.debian.org/status/fetch.php?pkg=mariadb-5.5&arch=s390x&ver=5.5.35-1&stamp=1392725213 MariaDB for s390x seem to build OK but there are some tests that fail:
Completed: Failed 3/2678 tests, 99.89% were successful.
Failing test(s): main.gis-precise perfschema.func_file_io perfschema.func_mutex
Do these actually indicate a real issue in the build? Could the root cause or the tests themselves be fixed?
I would rather not disable build tests in Debian packages as they are a good tool to spot possible errors in built binaries.