avoid segfault on submodule.*.path set to an empty "true"
Git fails due to a segmentation fault if a submodule path is empty.
Here is an example .gitmodules that will cause a segmentation fault:
[submodule "foo-module"]
path
url = http://host/repo.git
$ git status
Segmentation fault (core dumped)
This is because the parsing of "submodule.*.path" is not prepared to
see a value-less "true" and assumes that the value is always
non-NULL (parsing of "ignore" has the same problem).
Fix it by checking the NULL-ness of value and complain with
config_error_nonbool().
Signed-off-by: Jharrod LaFon <jlafon@eyesopen.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>