isogram: Add new test case
isogram: Add new test case

Adds a new test case where word starts with a unique letter
but have duplicate characters in the middle.

see: https://github.com/exercism/x-common/pull/743

smalley/python,exercism/xpython,exercism/xpython,mweb/python,behrtam/xpython,exercism/python,jmluy/xpython,mweb/python,pheanex/xpython,exercism/python,jmluy/xpython,N-Parsons/exercism-python,N-Parsons/exercism-python,smalley/python,pheanex/xpython,behrtam/xpython