When environment variable POSIXLY_CORRECT is set, the
"input -o output" syntax is not supported.
http://cygwin.com/ml/cygwin/2017-01/msg00036.html
Use "-i input -o output" syntax instead.
Signed-off-by: Steven Penny <svnpenn@gmail.com> Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>