This bug was fixed in the package ifupdown - 0.8.10ubuntu1.4
--------------- ifupdown (0.8.10ubuntu1.4) xenial; urgency=medium
* We are not even reading the contents of the per-interface state files when running ifquery, so there is no need to lock them. Not locking will allow ifquery to be called recursively from ifup and ifdown. (LP: #1701023)
-- Dan Streetman <email address hidden> Fri, 27 Apr 2018 08:56:12 -0400
This bug was fixed in the package ifupdown - 0.8.10ubuntu1.4
---------------
ifupdown (0.8.10ubuntu1.4) xenial; urgency=medium
* We are not even reading the contents of the per-interface state files
when running ifquery, so there is no need to lock them. Not locking
will allow ifquery to be called recursively from ifup and ifdown.
(LP: #1701023)
-- Dan Streetman <email address hidden> Fri, 27 Apr 2018 08:56:12 -0400