rails/rails — pull request #10759 by avk (2013-05-26 06:12:01+00:00)
Title: Make `to_sentence` ignore blank array elements

Array#to_sentence should not include blank elements in it's output as
they would not be part of a valid sentence.

["", "one", nil, "two", "", "three"].to_sentence
# => "one, two, and three"
# instead of
# => ", one, , two, , and three"