Simplified to find gemspecs for bundled gems (ruby#12709)

* Simplified to find gemspecs for bundled gems

Co-authored-by: Nobuyoshi Nakada <[email protected]>

tool/rbinstall.rb

@@ -1138,21 +1138,18 @@ class << (w = [])
     next unless /^(\S+)\s+(\S+).*/ =~ name
     gem = $1
     gem_name = "#$1-#$2"
-    # Try to find the original gemspec file
-    path = "#{srcdir}/.bundle/gems/#{gem_name}/#{gem}.gemspec"
-    unless File.exist?(path)
-      # Try to find the gemspec file for C ext gems
+    path = [
+      # gemspec that removed duplicated dependencies of bundled gems
+      "#{srcdir}/.bundle/gems/#{gem_name}/#{gem}.gemspec",
+      # gemspec for C ext gems, It has the original dependencies
       # ex .bundle/gems/debug-1.7.1/debug-1.7.1.gemspec
-      # This gemspec keep the original dependencies
-      path = "#{srcdir}/.bundle/gems/#{gem_name}/#{gem_name}.gemspec"
-      unless File.exist?(path)
-        # Try to find the gemspec file for gems that hasn't own gemspec
-        path = "#{srcdir}/.bundle/specifications/#{gem_name}.gemspec"
-        unless File.exist?(path)
-          skipped[gem_name] = "gemspec not found"
-          next
-        end
-      end
+      "#{srcdir}/.bundle/gems/#{gem_name}/#{gem_name}.gemspec",
+      # original gemspec generated by rubygems
+      "#{srcdir}/.bundle/specifications/#{gem_name}.gemspec"
+    ].find { |gemspec| File.exist?(gemspec) }
+    if path.nil?
+      skipped[gem_name] = "gemspec not found"
+      next
     end
     spec = load_gemspec(path, "#{srcdir}/.bundle/gems/#{gem_name}")
     unless spec.platform == Gem::Platform::RUBY