Only allow process that started server to shut it down.

lib/capybara/driver/webkit/browser.rb

@@ -111,14 +111,20 @@ class Capybara::Driver::Webkit
 
     def fork_server
       server_path = File.expand_path("../../../../../bin/webkit_server", __FILE__)
-
       pipe, @pid = server_pipe_and_pid(server_path)
-
-      at_exit { Process.kill("INT", @pid) }
-
+      register_shutdown_hook
       pipe
     end
 
+    def register_shutdown_hook
+      @owner_pid = Process.pid
+      at_exit do
+        if Process.pid == @owner_pid
+          Process.kill("INT", @pid)
+        end
+      end
+    end
+
     def server_pipe_and_pid(server_path)
       pipe = IO.popen(server_path)
       [pipe, pipe.pid]

spec/browser_spec.rb

@@ -32,4 +32,13 @@ describe Capybara::Driver::Webkit::Browser do
     io.string.should == "hello world\n"
   end
 
+  describe "forking" do
+    it "only shuts down the server from the main process" do
+      browser.reset!
+      pid = fork {}
+      Process.wait(pid)
+      expect { browser.reset! }.not_to raise_error
+    end
+  end
+
 end