downloader.rb: true symlink on cygwin

* tool/downloader.rb (Downloader.link_cache): on Cygwin, make true
  symlink only, which is provided by the OS.  as mingw/mswin ruby
  can't follow cygwin's pseudo symlink, it will fail on the same
  source tree.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58843 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 8 deletions

diff --git a/tool/downloader.rb b/tool/downloader.rb
index a8c47f02c7..0498e3f95c 100644
--- a/tool/downloader.rb
+++ b/tool/downloader.rb
@@ -225,15 +225,17 @@ class Downloader
   def self.link_cache(cache, file, name, verbose = false)
     return false unless cache and cache.exist?
     return true if cache.eql?(file)
-    begin
-      file.make_symlink(cache.relative_path_from(file.parent))
-    rescue SystemCallError
-    else
-      if verbose
-        $stdout.puts "made symlink #{name} to #{cache}"
-        $stdout.flush
+    if /cygwin/ !~ RUBY_PLATFORM or /winsymlink:nativestrict/ =~ ENV['CYGWIN']
+      begin
+        file.make_symlink(cache.relative_path_from(file.parent))
+      rescue SystemCallError
+      else
+        if verbose
+          $stdout.puts "made symlink #{name} to #{cache}"
+          $stdout.flush
+        end
+        return true
       end
-      return true
     end
     begin
       file.make_link(cache)