[ruby-core:19126] JRuby deprioritizing support for 1.8.7 behavior

Just FYI, we've pretty much made the decision that JRuby will not make 
1.8.7 API support a priority in the near term. We will continue to 
support 1.8.6 behavior and have started filling out 1.9 behavior, but we 
have seen no evidence that 1.8.7 compatibility is needed or desired by 
JRuby users.

Discussion is welcome, and if anyone has a compelling reason why we 
should support 1.8.7, we're willing to listen.

- Charlie