Run a test that fails during 'make test':
LD_LIBRARY_PATH=. ./ruby1.9.1 -Ilib -I. -I.ext/common tool/runruby.rb --extout=.ext bootstraptest/runner.rb --ruby="./ruby1.9.1" -v bootstraptest/test_thread.rb

Run a test that fails during 'make test-all':
LD_LIBRARY_PATH=. ./ruby1.9.1 -Ilib -I. -I.ext/common tool/runruby.rb
--extout=.ext test/drb/test_drb.rb -v
or even:
LD_LIBRARY_PATH=. ./ruby1.9.1 -Ilib -I. -I.ext/common tool/runruby.rb
--extout=.ext test/drb/test_drb.rb -v -n test_04 
