Use xstrfmt() to assign a formatted string to a ref record's
refname instead of xstrdup(). This helps save the overhead of
a local 'char' buffer as well as makes the test more compact.
Mentored-by: Patrick Steinhardt <ps@pks.im>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Chandra Pratap <chandrapratap3519@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>