Fix symlinks to '..' to fix rubygems improperly expanding symlinked
paths. Without this fix, some gems fail to install. This patch is applied in
rubygems 2.5.2, but ruby version 2.3.1 bundles an older version of rubygems
(2.5.1).

--- a/lib/rubygems/package.rb
+++ b/lib/rubygems/package.rb
@@ -383,7 +383,7 @@ def extract_tar_gz io, destination_dir, pattern = "*" # :nodoc:
           FileUtils.chmod entry.header.mode, destination
         end if entry.file?

-        File.symlink(install_location(entry.header.linkname, destination_dir), destination) if entry.symlink?
+        File.symlink(entry.header.linkname, destination) if entry.symlink?

         verbose destination
       end
diff --git a/test/rubygems/test_gem_package.rb b/test/rubygems/test_gem_package.rb
index 7848bc2..f287bd3 100644
--- a/test/rubygems/test_gem_package.rb
+++ b/test/rubygems/test_gem_package.rb
@@ -428,19 +428,25 @@ def test_extract_tar_gz_absolute
                  "#{@destination} is not allowed", e.message)
   end

-  def test_extract_tar_gz_symlink_absolute
+  def test_extract_tar_gz_symlink_relative_path
+    skip 'symlink not supported' if Gem.win_platform?
+
     package = Gem::Package.new @gem

     tgz_io = util_tar_gz do |tar|
-      tar.add_symlink 'code.rb', '/absolute.rb', 0644
+      tar.add_file    'relative.rb', 0644 do |io| io.write 'hi' end
+      tar.mkdir       'lib',         0755
+      tar.add_symlink 'lib/foo.rb', '../relative.rb', 0644
     end

-    e = assert_raises Gem::Package::PathError do
-      package.extract_tar_gz tgz_io, @destination
-    end
+    package.extract_tar_gz tgz_io, @destination

-    assert_equal("installing into parent path /absolute.rb of " +
-                 "#{@destination} is not allowed", e.message)
+    extracted = File.join @destination, 'lib/foo.rb'
+    assert_path_exists extracted
+    assert_equal '../relative.rb',
+                 File.readlink(extracted)
+    assert_equal 'hi',
+                 File.read(extracted)
   end

   def test_extract_tar_gz_directory
 <a href='/guix/log/?id=79a925f4e713d201eb5109bcf83b87c406c19484'>root</a>/<a href='/guix/log/tests?id=79a925f4e713d201eb5109bcf83b87c406c19484'>tests</a>/<a href='/guix/log/tests/networking.scm?id=79a925f4e713d201eb5109bcf83b87c406c19484'>networking.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/networking.scm?id=79a925f4e713d201eb5109bcf83b87c406c19484&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-10-30 18:15:54 -0400'>2019-10-30</span></td><td><a href='/guix/commit/tests/networking.scm?id=97bc3cbea5fc281a299c03eaaa3be5baf21ea673'>services: ntp: Ensure no double quotes are output to config file.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/networking.scm (ntp-server-&gt;string): Use the textual
representation of the values as printed by 'display' rather than 'write', to
avoid inserting double quotes in the generated config.
* tests/networking.scm (%ntp-server-sample): Add a comment and make one of the
options a string, to exercise the fix.
("ntp-server-&gt;string"): Move the expected value to the first argument.
("ntp configuration servers deprecated form"): Likewise.
("openntpd generated config string ends with a newline"): Likewise.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2019-09-08 23:15:32 +0900'>2019-09-08</span></td><td><a href='/guix/commit/tests/networking.scm?id=2625abc6aa5df66a6503e906b7592691452954f5'>services: openntpd: Add test for issue #3731.</a><span class='msg-avail'>...<span class='msg-tooltip'>See http://debbugs.gnu.org/cgi/bugreport.cgi?bug=37318.

* gnu/services/networking.scm (openntpd-configuration-&gt;string): New procedure,
extracted from top of the `openntpd-shepherd-service' to make it testable.
(openntpd-shepherd-service): Adapt following the move of the code to the above
procedure.
* tests/networking.scm: Add a test for the `openntpd-configuration-&gt;string'
procedure.
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2019-09-08 23:15:31 +0900'>2019-09-08</span></td><td><a href='/guix/commit/tests/networking.scm?id=5658ae8a0ad5d988765944b7e783b2bdc23a7f48'>services: ntp: Support different NTP server types and options.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/networking.scm (ntp-server-types): New enum.
(&lt;ntp-server&gt;): New record type.
(ntp-server-&gt;string): New procedure.
(%ntp-servers): Define in terms of &lt;htp-server&gt; records.  Use the first
entrypoint server as a pool instead of a list of static servers.  This is more
resilient since a new server of the pool can be interrogated on every
request.  Add the 'iburst' options.
(ntp-configuration-servers): Define a custom accessor that warns but honors
the now deprecated server format.
(&lt;ntp-configuration&gt;): Use it.
(%openntpd-servers): New variable,
(&lt;openntpd-configuration&gt;): Use it, as a pool ('servers' field) instead of a
regular server.
* tests/networking.scm: New file.
* Makefile.am (SCM_TESTS): Register it.
* doc/guix.texi: Update documentation.
</span></span></td><td>Maxim Cournoyer</td></tr>