Status#changed? is case-sensitive despite git config

[ghost]

Subject of the issue

When the git repo is configured to track files case-insensitively and a file name has a different letter case, Status#changed? will not report if the file has been modified.

Your environment

• git (1.11.0)
• ruby 2.7.3

Steps to reproduce

• init a new git repo
• (have default config core.ignoreCase true)
• commit FILE
• rename to file
• edit file
• in ruby-git, call Status#changed?("file")

Expected behaviour

expected to compare tracked file case-insensitively with given filename (ie "FILE".downcase == "file".downcase)

Actual behaviour

returns false