Don't emit empty alt.

Author: ioquatix

lib/rdoc/markup/to_html.rb

@@ -99,7 +99,7 @@ def handle_RDOCLINK url # :nodoc:
       gen_url CGI.escapeHTML(url), CGI.escapeHTML(text)
     when /^rdoc-image:/
       url, alt = $'.split(":", 2) # Split the string after "rdoc-image:" into url and alt
-      if alt
+      if alt && !alt.empty?
         %[<img src="#{CGI.escapeHTML(url)}" alt="#{CGI.escapeHTML(alt)}">]
       else
         %[<img src="#{CGI.escapeHTML(url)}">]