All processes that the Git main process spawns inherit the open file
descriptors of the main process. These leaked file descriptors can
cause problems.
Use the O_CLOEXEC flag similar to 05d1ed61 to fix the leaked file
descriptors.
Signed-off-by: Lars Schneider <larsxschneider@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>