Merge pull request libgit2#4112 from cbargren/fix/proxy-env-vars

Add support for lowercase proxy environment variables

Author: Edward Thomson

src/remote.c

@@ -770,8 +770,12 @@ int git_remote__get_http_proxy(git_remote *remote, bool use_ssl, char **proxy_ur
 		goto found;
 	}
 
-	/* HTTP_PROXY / HTTPS_PROXY environment variables */
-	error = git__getenv(&val, use_ssl ? "HTTPS_PROXY" : "HTTP_PROXY");
+	/* http_proxy / https_proxy environment variables */
+	error = git__getenv(&val, use_ssl ? "https_proxy" : "http_proxy");
+
+	/* try uppercase environment variables */
+	if (error == GIT_ENOTFOUND)
+		error = git__getenv(&val, use_ssl ? "HTTPS_PROXY" : "HTTP_PROXY");
 
 	if (error < 0) {
 		if (error == GIT_ENOTFOUND) {