templater: do not process \-escapes at parsestring() (issue4290) This patch brings back pre-2.8.1 behavior. The result of parsestring() is stored in templater's cache, t.cache, and then it is parsed as a template string by compiletemplate(). So t.cache should keep an unparsed string no matter if it is sourced from config value. Otherwise backslashes would be processed twice. The test vector is borrowed from 64b4f0cd7336.