Instead of using strbuf to create a message string in case a path is
too long for our fixed-size buffer, replace that buffer with a strbuf
and thus get rid of the limitation.
Helped-by: Duy Nguyen <pclouds@gmail.com> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>