* array.c (rb_ary_fill): tail elements were vanished when the middle
part of array was filled. (ie: [0,1,2,3,4].fill(-1,2,1) => [0,1,-1])
* test/ruby/test_array.rb (test_fill): added.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@9541 b2dd03c8-39d4-4d8f-98ff-823fe69b080e