Allow ruby-head to fail
Allow ruby-head to fail

MSP-11141

ruby-head (ruby-2.3.0-dev) is currently failing due to "LoadError:
cannot load such file -- test/unit/testcase", which is required by
activesupport-3.2.21/lib/active_support/test_case.rb.  activesupport
3.2.21 may not be ruby 2.3 compatible.

rapid7/metasploit-cache,rapid7/metasploit-cache,rapid7/metasploit-cache,rapid7/metasploit-cache