The execdriver pipes setup uses OS pipes with fds so that they can be
chown'ed to the remapped root user for proper access. Recent flakiness
in certain short-lived tests (usually via the "exec" path) reveals that
the copy routines are not completing before exit/tear-down.
This fix adds synchronization and proper closure such that these
routines exit successfully.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Upstream-commit: 995386735c2fe47ebb144f95adbc8eb1341ac48b
Component: engine
5e9f05d546