Exclude transient MRI tests

Author: eregon

test/mri/excludes/TestIO_M17N.rb

@@ -69,3 +69,4 @@
 exclude :test_write_conversion_fixenc, "needs investigation"
 exclude :test_stdout, "<nil> expected but was"
 exclude :test_stderr, "<nil> expected but was"
+exclude :test_popenv_r_enc_enc_in_opt2, "transient: <\"\\x{8EA1}\"> expected but was"

test/mri/excludes/TestSignal.rb

@@ -9,3 +9,4 @@
 exclude :test_trap, "ArgumentError: Unsupported command ''"
 exclude :test_signal2, "ArgumentError: ArgumentError"
 exclude :test_trap_system_default, "ArgumentError: Signal already used by VM or OS: SIGQUIT"
+exclude :test_signal, "transient: RuntimeError: Interrupt"

test/mri/excludes/TestTimeExtension.rb

@@ -3,3 +3,4 @@
 exclude :test_xmlschema_encode, "needs investigation"
 exclude :test_iso8601, "needs investigation"
 exclude :test_xmlschema, "needs investigation"
+exclude :test_rfc2822_nonlinear, "transient: ArgumentError expected but nothing was raised."