Do not implicitely convert a configuration value to text if the value is the result of just a variable expansion. This is technically a breaking change. But no known client code uses the old behaviour.

# -*- coding: utf-8; -*-

__comment1 = "Comment 1"
key1 = "the value"
key2 = 2
key3 = 5.7
key4 = true
key5 = false
key6 = 0o377
__comment2 = "Comment no 2"
key7 = "Umlaute: ÄÖÜäöüß"