Include proxy env variables in git operations if set

Signed-off-by: Hidde Beydals <hello@hidde.co>

git/operations.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"os"
 	"os/exec"
 	"strings"
 
@@ -289,7 +290,18 @@ func execGitCmd(ctx context.Context, dir string, out io.Writer, args ...string)
 }
 
 func env() []string {
-	return []string{"GIT_TERMINAL_PROMPT=0"}
+	env := []string{"GIT_TERMINAL_PROMPT=0"}
+
+	// include proxy environment variables if set
+	for _, e := range os.Environ() {
+		pair := strings.SplitN(e, "=", 2)
+		if pair[0] != "HTTP_PROXY" && pair[0] != "HTTPS_PROXY" && pair[0] != "NO_PROXY" {
+			continue
+		}
+		env = append(env, e)
+	}
+
+	return env
 }
 
 // check returns true if there are changes locally.