gitignore patterns are always treated case sensitively

What steps will reproduce the problem?

1. create .gitignore with a file pattern: *.txt
2. create files: 1.txt, 2.Txt and 3.TXT

What is the expected output?

What do you see instead?

There is the same result when I try to use global ignore file.

What version of TortoiseGit and Git are you using?

TortoiseGit 2.4.0.2 (64-bit)

git version 2.8.2.windows.1 (64-bit)

On what operating system?

Windows 7 Pro 64-bit