Correctly parse ImageMagick bottle version

Commit 2695821e98 ("Only use the bottle if its version is up-to-date")
essentially broke the ImageMagick bottle, because the version parsing
logic returns "1" as the bottle version.

Fixing this requires only a slight modification to the bottle URL regex;
includes a test.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/extend/pathname.rb

@@ -165,7 +165,7 @@ class Pathname
     return $1 if $1
 
     # brew bottle style e.g. qt-4.7.3-bottle.tar.gz
-    /-((\d+\.)*\d+)-bottle$/.match stem
+    /-((\d+\.)*\d+(-\d)*)-bottle$/.match stem
     return $1 if $1
 
     # eg. otp_src_R13B (this is erlang's style)

Library/Homebrew/test/test_versions.rb

@@ -164,4 +164,9 @@ class VersionTests < Test::Unit::TestCase
     check 'https://downloads.sourceforge.net/project/machomebrew/Bottles/qt-4.7.3-bottle.tar.gz',
       '4.7.3'
   end
+
+  def test_imagemagick_bottle_style
+    check 'http://downloads.sf.net/project/machomebrew/Bottles/imagemagick-6.7.1-1-bottle.tar.gz',
+      '6.7.1-1'
+  end
 end