Jeff King authored Mar 22, 2015 and Junio C Hamano committed Mar 22, 2015

When we read from a trailer.*.command sub-program, the
current code uses run_command followed by a pipe read, which
can result in deadlock (though in practice you would have to
have a large trailer for this to be a problem). The current
code also leaks the file descriptor for the pipe to the
sub-command.

Instead, let's use capture_command, which makes this simpler
(and we can get rid of our custom helper).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>