git clone hangs on windows, and file.write would return errno 22 inside
of mercurial's windows.winstdout wrapper class. This patch sets stdout's
mode to binary, fixing both issues.
[fc: cleaned up]
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>