This patch standardizes calls to system() where external git tools are
called. Instead of system("git foo ... "), use system(qw(git foo ...)).
All calls are made without the use of an 'sh -c' process to split the
arguments.
Signed-off-by: Ben Walton <bwalton@artsci.utoronto.ca> Signed-off-by: Junio C Hamano <gitster@pobox.com>