node to page: Fixe index page translation issues

Updates #2297

hugolib/page.go

@@ -1608,19 +1608,19 @@ func (p *Page) Lang() string {
 	return p.lang
 }
 
-func (p *Page) isTranslation(candidate *Page) bool {
+func (p *Page) isNewTranslation(candidate *Page) bool {
 	if p == candidate || p.Kind != candidate.Kind {
 		return false
 	}
 
-	if p.lang != candidate.lang || p.language != p.language {
-		return false
-	}
-
 	if p.Kind == KindPage || p.Kind == kindUnknown {
 		panic("Node type not currently supported for this op")
 	}
 
+	if p.language.Lang == candidate.language.Lang {
+		return false
+	}
+
 	// At this point, we know that this is a traditional Node (home page, section, taxonomy)
 	// It represents the same node, but different language, if the sections is the same.
 	if len(p.sections) != len(candidate.sections) {
@@ -1633,6 +1633,13 @@ func (p *Page) isTranslation(candidate *Page) bool {
 		}
 	}
 
+	// Finally check that it is not already added.
+	for _, translation := range candidate.translations {
+		if p == translation {
+			return false
+		}
+	}
+
 	return true
 
 }
@@ -1717,9 +1724,13 @@ func (p *Page) addLangFilepathPrefix(outfile string) string {
 }
 
 func sectionsFromFilename(filename string) []string {
+	var sections []string
 	dir, _ := filepath.Split(filename)
 	dir = strings.TrimSuffix(dir, helpers.FilePathSeparator)
-	sections := strings.Split(dir, helpers.FilePathSeparator)
+	if dir == "" {
+		return sections
+	}
+	sections = strings.Split(dir, helpers.FilePathSeparator)
 	return sections
 }