Rewrite spec to test relative path
Rewrite spec to test relative path

spec of InsensitiveSearch
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- Modify the context 'when passed a relative path of existence'.
  - Rename it 'when passed a relative path'.
  - Insert the content of the previous context as 'where plural files and directories exist'.

indeep-xyz/ruby-insensitive-search,indeep-xyz/ruby-insensitive-search