gistfile1.txt

$ ruby -v test.rb 
ruby 1.8.7 (2009-06-12 patchlevel 174) [i686-linux]
["image", "# src = map.gif\n# relative_height = 100\n"]
["image\r", "# src = map.gif\r\n# relative_height = 100\r\n"]

gistfile2.txt

$ ruby -v test.rb
ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32]
["image", "# src = map.gif\n# relative_height = 100\n"]
["image\r", "# src = map.gif\r\n# relative_height = 100\r\n"]

test.rb

# rd2rabbit-lib.rb:131
def match(element)
	content = []
	element.each_line do |line|
		content << line
	end
	content_str = content.join("")
	/\A#\s*([^\n]+)(?:\n)?(?m:(.*)?)\z/ =~ content_str
	return $1, $2.to_s
end

[
"#image\n# src = map.gif\n# relative_height = 100\n",
"#image\r\n# src = map.gif\r\n# relative_height = 100\r\n"
].each do |element|
	p match(element)
end

worked-on-linux.patch

Index: lib/rabbit/parser/rd/rd2rabbit-lib.rb
===================================================================
--- lib/rabbit/parser/rd/rd2rabbit-lib.rb	(リビジョン 1371)
+++ lib/rabbit/parser/rd/rd2rabbit-lib.rb	(作業コピー)
@@ -127,9 +127,9 @@
         def apply_to_Verbatim(element)
           content = []
           element.each_line do |line|
-            content << line
+            content << line.chomp
           end
-          content_str = content.join("")
+          content_str = content.join("\n")
           /\A#\s*([^\n]+)(?:\n)?(?m:(.*)?)\z/ =~ content_str
           apply_to_extension("block_verbatim", $1, $2.to_s, content_str)
         end