[rubygems/rubygems] Fix crash when installing gems with symlinks

If BUNDLE_PATH is configured to a symlinked path, installing gems with
symlinks would crash with an error like this:

```
Gem::Package::SymlinkError: installing symlink 'man/man0/README.markdown' pointing to parent path /usr/home/stevewi/srv/mail/lib/tools/.vendor/ruby/3.1.0/gems/binman-5.1.0/README.markdown of /srv/mail/lib/tools/.vendor/ruby/3.1.0/gems/binman-5.1.0 is not allowed
```

This commit fixes the problem by changing the bundle path to be the
realpath of the configured value, right after we're sure the path has
been created.

https://github.com/rubygems/rubygems/commit/3cd3dd142a

2 files changed, 36 insertions, 2 deletions

diff --git a/spec/bundler/commands/install_spec.rb b/spec/bundler/commands/install_spec.rb
index 07585237e3..4a48187db0 100644
--- a/spec/bundler/commands/install_spec.rb
+++ b/spec/bundler/commands/install_spec.rb
@@ -969,4 +969,37 @@ RSpec.describe "bundle install with gem sources" do
       expect(last_command).to be_success
     end
   end
+
+  context "with a symlinked configured as bundle path and a gem with symlinks" do
+    before do
+      symlinked_bundled_app = tmp("bundled_app-symlink")
+      File.symlink(bundled_app, symlinked_bundled_app)
+      bundle "config path #{File.join(symlinked_bundled_app, ".vendor")}"
+
+      binman_path = tmp("binman")
+      FileUtils.mkdir_p binman_path
+
+      readme_path = File.join(binman_path, "README.markdown")
+      FileUtils.touch(readme_path)
+
+      man_path = File.join(binman_path, "man", "man0")
+      FileUtils.mkdir_p man_path
+
+      File.symlink("../../README.markdown", File.join(man_path, "README.markdown"))
+
+      build_repo4 do
+        build_gem "binman", :path => gem_repo4("gems"), :lib_path => binman_path, :no_default => true do |s|
+          s.files = ["README.markdown", "man/man0/README.markdown"]
+        end
+      end
+    end
+
+    it "installs fine" do
+      install_gemfile <<~G
+        source "#{file_uri_for(gem_repo4)}"
+
+        gem "binman"
+      G
+    end
+  end
 end
diff --git a/spec/bundler/support/builders.rb b/spec/bundler/support/builders.rb
index aca31638ac..91f0106d7d 100644
--- a/spec/bundler/support/builders.rb
+++ b/spec/bundler/support/builders.rb
@@ -484,7 +484,7 @@ module Spec
         end
 
         @spec.authors = ["no one"]
-        @spec.files = @files.keys
+        @spec.files += @files.keys
 
         case options[:gemspec]
         when false
@@ -589,7 +589,8 @@ module Spec
 
     class GemBuilder < LibBuilder
       def _build(opts)
-        lib_path = super(opts.merge(:path => @context.tmp(".tmp/#{@spec.full_name}"), :no_default => opts[:no_default]))
+        lib_path = opts[:lib_path] || @context.tmp(".tmp/#{@spec.full_name}")
+        lib_path = super(opts.merge(:path => lib_path, :no_default => opts[:no_default]))
         destination = opts[:path] || _default_path
         FileUtils.mkdir_p(lib_path.join(destination))