GitLab

When a new label is created, it is created with a proxy in a circular
ref count that is broken by replacement. However if the label is not
used it will never be replaced and the circular ref count will never
be broken resulting in a leak.

BugLink: http://bugs.launchpad.net/bugs/1660834

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Brad Figg <brad.figg@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>