Fix random EPIPE failure in SIGINT restore tests (#1191)

Rescue Errno::EPIPE in test_sigint_restore_default and
test_sigint_restore_block. The child process may exit before
assert_in_out_err finishes writing "exit\n" to its stdin pipe,
which is a race condition in the test setup, not an IRB bug.

Author: k0kubun

test/irb/test_init.rb

@@ -107,13 +107,17 @@ def test_sigint_restore_default
       # IRB should restore SIGINT handler
       status = assert_in_out_err(bundle_exec + %w[-W0 -rirb -e Signal.trap("SIGINT","DEFAULT");binding.irb;loop{Process.kill("SIGINT",$$)} -- -f --], "exit\n", //, //)
       Process.kill("SIGKILL", status.pid) if !status.exited? && !status.stopped? && !status.signaled?
+    rescue Errno::EPIPE
+      # The child process may exit before the parent finishes writing to stdin
     end
 
     def test_sigint_restore_block
       bundle_exec = ENV.key?('BUNDLE_GEMFILE') ? ['-rbundler/setup'] : []
       # IRB should restore SIGINT handler
       status = assert_in_out_err(bundle_exec + %w[-W0 -rirb -e x=false;Signal.trap("SIGINT"){x=true};binding.irb;loop{Process.kill("SIGINT",$$);if(x);break;end} -- -f --], "exit\n", //, //)
       Process.kill("SIGKILL", status.pid) if !status.exited? && !status.stopped? && !status.signaled?
+    rescue Errno::EPIPE
+      # The child process may exit before the parent finishes writing to stdin
     end
 
     def test_no_color_environment_variable