tests: remove regular expression matching for Python 2.6 This effectively reverts 52cca17ac523. Some lines still have (re) due to variable length port numbers. There's not much we can do about that. But at least this change removes most of the ugliness.

branchmap: remove use of buffer() to support Python 2.6 The use of buffer() was added in 7359157b9e46 to support Python 2.6, which we no longer support.

py3: remove delayed import of importlib All supported versions of Python now have importlib. This effectively reverts b85fa6bf298b.

tests: use context manager form of assertRaises Support for using unittest.TestCase.assertRaises as a context manager was added in Python 2.7. This form is more readable, especially for complex tests. While I was here, I also restored the use of assertRaisesRegexp, which was removed in c6921568cd20 for Python 2.6 compatibility.

obsolete: use 2 argument form of enumerate() The 2 argument form of enumerate was added in Python 2.6. This change effectively reverts 10880c8aad85.

tests: remove special handling for undefined memoryview 'memoryview' was introduced in Python 2.7. 4adc090fa2fb added code to filterpyflakes.py to ignore "undefined name 'memoryview'" pyflakes warnings. Since we no longer support <Python 2.7, we can remove this workaround.

encoding: remove workaround for locale.getpreferredencoding() locale.getpreferredencoding() was buggy in OS X for Python <2.7. Since we no longer support Python <2.7, we no longer need this workaround. This essentially reverts 2be70ca17311.

mail: remove code to support < Python 2.7 This code was added in 594b98846ce1. Since we no longer support Python <2.7, it can be removed.

help: clarify that colons are allowed in fingerprints values This was suggested by Lars Rohwedder in issue5559.

sslutil: tweak the legacy [hostfingerprints] warning message Lars Rohwedder noted in issue5559 that the previous wording was confusing. I agree.