Adding a : isn't sufficient

It quite often appears after IPv4 hosts. A variation of https://www.debuggex.com/r/bx8G7msBKV_8xcHZv perhaps.

FAIL: testSampleRegexsAPACHE-AUTH (fail2ban.tests.samplestestcase.FilterSamplesRegex)
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Traceback (most recent call last):
  File "./fail2ban/tests/samplestestcase.py", line 123, in testFilter
    self.assertEqual(host, faildata.get("host", None))
AssertionError: '127.0.0.1:51380' != u'127.0.0.1'