Strip any ANSI escape codes from git command output

[warrenfalk]

Strip ANSI escape codes from all git output.

Previous attempts to set environment variables to tell git not to output these do not always work. On my installation using git with msys2, git continues to emit the color codes and breaks GitExtensions' diff output and other things. This commit fixes the issue cleanly.

[jbialobr]

Is it possible to determine whether the current git configuration results in emitting ANSI escape codes? (Perhaps perform some simple command) If yes, we could do stripping only when needed.

[warrenfalk]

That was my first approach and there were a couple problems with it.

1. Git is not the source of all of its output. A commit hook on a server, can also output escape codes, and server scripts cannot be aware of local environments.
2. I was unable to find any reliable way to even determine what git would do. It is possible to check the config and try to guess, but trying to guess what git may do today and in the future is fragile. This fix makes it work once and for all.

You could try to run every command and see if that command outputs escape codes, but not every command even does it every time.

Plus git may change in the future how it decides when to output escape codes making any attempts to detect this break. You'd then need to re-research the problem at that point and use a version-dependent algorithm to check.

If performance is a concern, I did check that the regex returns the original string when it finds no match. And since the regex is compiled and optimized it should need only to see if the string contains char code 27, and return the original if not.

[jbialobr]

Thank you for the thorough explanation.