This is wrong by itself. In order to fix this, we need to grep for "65535" in rlib/rsre.
There are some non-trivial issues around this problem: the format of compiled regular expressions changed between micro CPython version. This is going to be somewhat a mess, because we suddenly can't rely any more on the CPython's re module in order to precompile regular expressions, or when running tests, for example.
For example, I may be wrong, but I suspect that the test you added only works if the host CPython is at least 2.7.4, not if it's an older version.