erlang/otp — pull request #366 by fenollp (2014-05-13 22:55:41+00:00)
Title: Specify the spec of lists:append/2

Adding to the expected behaviour of '++' on proper lists we have
* 4 = [] ++ 4
* and [1|4] = [1] ++ 4

The spec should mention this behaviour on improper lists.