Removed unnecessary regex in code block plugin

plugins/code_block.rb

@@ -50,7 +50,6 @@ module Jekyll
     include HighlightCode
     include TemplateWrapper
     CaptionUrlTitle = /(\S[\S\s]*)\s+(https?:\/\/\S+|\/\S+)\s*(.+)?/i
-    CaptionUrl = /(\S[\S\s]*)\s+(https?:\/\/\S+|\/\S+)/i
     Caption = /(\S[\S\s]*)/
     def initialize(tag_name, markup, tokens)
       @title = nil
@@ -63,10 +62,7 @@ module Jekyll
       end
       if markup =~ CaptionUrlTitle
         @file = $1
-        @caption = "<figcaption><span>#{$1}</span><a href='#{$2}'>#{$3}</a></figcaption>"
-      elsif markup =~ CaptionUrl
-        @file = $1
-        @caption = "<figcaption><span>#{$1}</span><a href='#{$2}'>link</a></figcaption>"
+        @caption = "<figcaption><span>#{$1}</span><a href='#{$2}'>#{$3 || 'link'}</a></figcaption>"
       elsif markup =~ Caption
         @file = $1
         @caption = "<figcaption><span>#{$1}</span></figcaption>\n"