fix: Don't double backslashes in shellQuote

internal/cmd/shellquote.go

@@ -24,18 +24,12 @@ func shellQuote(s string) string {
 		inSingleQuotes := false
 		for _, b := range []byte(s) {
 			switch b {
-			case backslash:
-				if !inSingleQuotes {
-					result = append(result, singleQuote)
-					inSingleQuotes = true
-				}
-				result = append(result, backslash, backslash)
 			case singleQuote:
 				if inSingleQuotes {
 					result = append(result, singleQuote)
 					inSingleQuotes = false
 				}
-				result = append(result, '\\', singleQuote)
+				result = append(result, backslash, singleQuote)
 			default:
 				if !inSingleQuotes {
 					result = append(result, singleQuote)

internal/cmd/shellquote_test.go

@@ -14,8 +14,10 @@ func TestShellQuote(t *testing.T) {
 		`'`:           `\'`,
 		`''`:          `\'\'`,
 		`'a'`:         `\''a'\'`,
-		`\`:           `'\\'`,
-		`\a`:          `'\\a'`,
+		`\`:           `'\'`,
+		`\'`:          `'\'\'`,
+		`\a`:          `'\a'`,
+		`\n`:          `'\n'`,
 		`$a`:          `'$a'`,
 		`a`:           `a`,
 		`a/b`:         `a/b`,