When --recursive was added to "submodule foreach" in commit 15fc56a (git
submodule foreach: Add --recursive to recurse into nested submodules,
2009-08-19), the error message when the script returns a non-zero status
was not updated to contain $prefix to show the full path. Fix this.
Signed-off-by: John Keeping <john@keeping.me.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>