Commit
578625fa91 (config: add '--name-only' option to list only
variable names, 2015-08-10) modified format_config() such that it
returned from the middle of the function when showing only keys,
resulting in ugly code structure.
Reorganize the if statements and dealing with the key-value delimiter to
make the function easier to read.
Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>