Log Message:
Updated py-idna to 2.6.

2.6 (2017-08-08)
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- Allows generation of IDNA and UTS 46 table data for different
  versions of Unicode, by deriving properties directly from
  Unicode data.
- Ability to generate RFC 5892/IANA-style table data
- Diagnostic output of IDNA-related Unicode properties and
  derived calculations for a given codepoint
- Support for idna.__version__ to report version
- Support for idna.idnadata.__version__ and
  idna.uts46data.__version__ to report Unicode version of
  underlying IDNA and UTS 46 data respectively.