The symlink auditor is sometimes cached too long, and can be confused into allowing write access to outside the repo.
External References: https://www.mercurial-scm.org/wiki/WhatsNew#Mercurial_4.3_.2F_4.3.1_.282017-08-10.29
Acknowledgments: Name: the Mercurial Security Team
Created mercurial tracking bugs for this issue: Affects: fedora-all [bug 1480454]
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2017:2489 https://access.redhat.com/errata/RHSA-2017:2489