Update gemfile for msys2

Author: sebastianrakel

Gemfile

@@ -4,7 +4,18 @@ def location_for(place)
   if place =~ /^((?:git[:@]|https:)[^#]*)#(.*)/
     [{ :git => $1, :branch => $2, :require => false }]
   elsif place =~ /^file:\/\/(.*)/
-    ['>= 0', { :path => File.expand_path($1), :require => false }]
+    raw_path = $1
+
+    expanded_path =
+      if Gem.win_platform?
+        normalized = raw_path.sub(%r{^/([A-Za-z]:/)}, '\1')
+        normalized = normalized.tr('/', '\\')
+        File.expand_path(normalized)
+      else
+        File.expand_path(raw_path)
+      end
+    
+    ['>= 0', { :path => expanded_path, :require => false }]
   else
     [place, { :require => false }]
   end