t7502: test commit.status, --status and --no-status

t7502: test commit.status, --status and --no-status

Make sure that the status information:

 - is shown as before without configuration nor command line option;

 - is shown if commit.status is set to true and no command line option
   is given, or --status is explicitly given;

 - is not shown if commit.status is set to false and no command line
   option is given, or --no-status is explicitly given.

Also make sure that the way lines taken from the custom --template appear
in the log message editor is not changed at all.

Signed-off-by: Junio C Hamano <gitster@pobox.com>