The email addresses read from .mailmap are downcased before being
inserted into the mailmap data structure, which undesirably loses
information. It is impossible, for instance, to map <first.last@host>
to <First.Last@host>. Demonstrate this problem.
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>