Pend spec broken on JRuby

spec/rspec/support_spec.rb

@@ -196,7 +196,20 @@ def object.some_method
       end
 
       if defined?(Fiber) && RUBY_VERSION.to_f >= 2.0
-        it "shares data across fibres" do
+        broken_on_jruby =
+          if RSpec::Support::Ruby.jruby?
+            "As Fibre.new creates a new thread on JRuby this is currently " \
+            "broken. There are alternative implementations that do work but " \
+            "they cause issues for mocks, so given this is a minor edge case " \
+            "and thread data is already broken, its acceptable. Pending " \
+            "because future JRuby may fix this. see: "\
+            "https://github.com/jruby/jruby/issues/1806 and " \
+            "https://github.com/rspec/rspec-support/pull/610"
+          else
+            false
+          end
+
+        it "shares data across fibres", pending: broken_on_jruby do
           RSpec::Support.thread_local_data[:__for_test] = :oh_hai
 
           Fiber.new do