RSS: fall back to LogoUrl for RssLogoUrl

Changelog

@@ -3,6 +3,7 @@ Changes for bugfix release:
 * closing div for class wikibody was missing at some places, added
 * put <hr> class wikilinerc inside of div for class wikirc
 * fix EditHash
+* RSS: fall back to LogoUrl for RssLogoUrl
 
 Changes for release 1.2.0 (November 05, 2017):
 * switch DTD to HTML 4.0.1 Transitional

wiki.pl

@@ -919,6 +919,15 @@ sub GetRcRss {
 RSS
   ($headList, $items) = &GetRc(0, @_);
   $rssHeader .= $headList;
+  if (! $RssLogoUrl) {
+    $RssLogoUrl = $FullUrl;
+    if ($LogoUrl =~ /^\//) {
+      $RssLogoUrl =~ s/^(http:\/\/[^\/]*)(\/.*)$/$1/;
+      $RssLogoUrl .= $LogoUrl;
+    } else {
+      $RssLogoUrl = $LogoUrl;
+    }
+  }
   return <<RSS ;
 $rssHeader
             </rdf:Seq>