t4014: invoke format-patch with --stdout where intended
t4014: invoke format-patch with --stdout where intended

The test wrote something along the lines of 0001-foo.patch to output,
which of course never contained a signature.  Luckily the tested
behaviour is actually present.

Signed-off-by: Thomas Rast <18f23ef7096473d837b7404952f13710423b8b63@student.ethz.ch>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git