* jk/submodule-c-credential:
submodule: stop sanitizing config options
submodule: use prepare_submodule_repo_env consistently
submodule--helper: move config-sanitizing to submodule.c
submodule: export sanitized GIT_CONFIG_PARAMETERS
t5550: break submodule config test into multiple sub-tests
t5550: fix typo in $HTTPD_URL
git_config_push_parameter: handle empty GIT_CONFIG_PARAMETERS
git: submodule honor -c credential.* from command line
quote: implement sq_quotef()
submodule: fix segmentation fault in submodule--helper clone
submodule: fix submodule--helper clone usage
submodule: check argc count for git submodule--helper clone
submodule: don't pass empty string arguments to submodule--helper clone