Merge pull request #806 from sstephenson/bundle-rehash

Avoid running `rbenv rehash` multiple times during `bundle install`

rbenv.d/exec/gem-rehash/rubygems_plugin.rb

@@ -6,13 +6,38 @@ hook = lambda do |installer|
       `rbenv rehash`
     end
   rescue
-    warn "rbenv: error in gem-rehash (#{$!})"
+    warn "rbenv: error in gem-rehash (#{$!.class.name}: #{$!.message})"
   end
 end
 
-begin
-  Gem.post_install(&hook)
-  Gem.post_uninstall(&hook)
-rescue
-  warn "rbenv: error installing gem-rehash hooks (#{$!})"
+if defined?(Bundler::Installer) && Bundler::Installer.respond_to?(:install)
+  Bundler::Installer.class_eval do
+    class << self
+      alias install_without_rbenv_rehash install
+      def install(root, definition, options = {})
+        begin
+          if Gem.default_path.include?(Bundler.bundle_path.to_s)
+            bin_dir = Gem.bindir(Bundler.bundle_path.to_s)
+            bins_before = File.exist?(bin_dir) ? Dir.entries(bin_dir).size : 2
+          end
+        rescue
+          warn "rbenv: error in Bundler post-install hook (#{$!.class.name}: #{$!.message})"
+        end
+
+        result = install_without_rbenv_rehash(root, definition, options)
+
+        if bin_dir && File.exist?(bin_dir) && Dir.entries(bin_dir).size > bins_before
+          `rbenv rehash`
+        end
+        result
+      end
+    end
+  end
+else
+  begin
+    Gem.post_install(&hook)
+    Gem.post_uninstall(&hook)
+  rescue
+    warn "rbenv: error installing gem-rehash hooks (#{$!.class.name}: #{$!.message})"
+  end
 end