facebook/presto — pull request #1459 by martint (2014-07-03 00:34:22+00:00)
Title: Fix NULLIF semantics

NULLIF now correctly returns a result with the type of the first argument. For instance:

NULLIF(1.0, 2) => 1.0
NULLIF(1, 2.0) => 1

Previously, the type of the result was the common supertype of both arguments