i686-apple-darwin9-gcc-4.0.1 (GCC) 4.0.1 (Apple Inc. build 5490) compiler
(and probably others) mistakenly thinks variable failed_errno is used
before assigned. Work it around by giving it a fake initialization.
Signed-off-by: David Soria Parra <dsp@php.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>