hugolib: Must update PathSpec on SiteInfo per language

hugolib/hugo_sites_test.go

@@ -78,6 +78,8 @@ func doTestMultiSitesMainLangInRoot(t *testing.T, defaultInSubDir bool) {
 		require.Equal(t, "", frSite.Info.LanguagePrefix)
 	}
 
+	require.Equal(t, "/blog/en/foo", enSite.Info.pathSpec.RelURL("foo", true))
+
 	doc1en := enSite.Pages[0]
 	doc1fr := frSite.Pages[0]
 

hugolib/site.go

@@ -823,6 +823,7 @@ func (s *Site) setCurrentLanguageConfig() error {
 	viper.Set("currentContentLanguage", s.Language)
 	// Cache the current config.
 	helpers.InitConfigProviderForCurrentContentLanguage()
+	s.Info.pathSpec = helpers.CurrentPathSpec()
 	return tpl.SetTranslateLang(s.Language)
 }