Add support for GIT_DIR and GIT_WORK_TREE environment variables (#1191)

* Use git env variables for git dir and git workdir

* Add changes to CHANGELOG.md

* Fix indentation

* Add link to PR

Co-authored-by: Stephan D <[email protected]>

Author: splitDEV

Diff for: CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * stack popups ([#846](https://github.com/extrawurst/gitui/issues/846))
 * file history log [[@cruessler](https://github.com/cruessler)] ([#381](https://github.com/extrawurst/gitui/issues/381))
 * termux support on andriod [[@PeroSar](https://github.com/PeroSar)] ([#1139](https://github.com/extrawurst/gitui/issues/1139))
+* use `GIT_DIR` and `GIT_WORK_DIR` from environment if set ([#1191](https://github.com/extrawurst/gitui/pull/1191))
 * new [FAQ](./FAQ.md)s page
 
 ### Fixed

Diff for: src/args.rs

@@ -46,13 +46,15 @@ pub fn process_cmdline() -> Result<CliArgs> {
 				.help("Set the git directory")
 				.short("d")
 				.long("directory")
+				.env("GIT_DIR")
 				.takes_value(true),
 		)
 		.arg(
 			Arg::with_name("workdir")
 				.help("Set the working directory")
 				.short("w")
 				.long("workdir")
+				.env("GIT_WORK_TREE")
 				.takes_value(true),
 		);