deadlock when map-ing multiple threads

[cldwalker]

As encountered in sferik/twitter-ruby#332, the following causes debugger to raise an internal error:

threads = []
[1,2,3].each {|obj| threads << Thread.new { yield obj } }
threads.map(&:value)

I don't have time to look into this. Pull requests welcome to fix this.
@Gissues:{"order":75,"status":"notstarted"}

[deivid-rodriguez]

@cldwalker That code raises #<LocalJumpError: no block given (yield)> with both 1.9.3 and 2.0.0. Is the problem that debugger deadlocks instead of rising the same error?