prevent minitest from printing a --seed run option

See the first FIXME comment in the patch for the rationale.

activesupport/lib/active_support/test_case.rb

@@ -16,6 +16,16 @@
 rescue LoadError
 end
 
+# FIXME: We force sorted test order below, but minitest includes --seed SEED in
+# the printed run options, which could be misleading, since users could assume
+# from that trace that tests are being randomized.
+MiniTest::Unit.class_eval do
+  alias original_help help
+  def help
+    original_help.sub(/--seed\s+\d+\s*/, '')
+  end
+end
+
 module ActiveSupport
   class TestCase < ::MiniTest::Unit::TestCase
     Assertion = MiniTest::Assertion
@@ -26,8 +36,8 @@ def self.for_tag(tag)
       yield if $tags[tag]
     end
 
-    # FIXME: we have tests that depend on run order, we should fix that and
-    # remove this method.
+    # FIXME: We have tests that depend on run order, we should fix that and
+    # remove this method (and remove the MiniTest::Unit help hack above).
     def self.test_order # :nodoc:
       :sorted
     end