In the common case where the user is using /var/lib/docker and
an image with less than 60 layers, forking is not needed. Calculate
whether absolute paths can be used and avoid forking to mount in
those cases.
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
Upstream-commit: c13a985fa1196a5ed782d5ac68a4bbb68dd529ca
Component: engine