rootless: launch rootlesskit with --propagation=rslave

The propagation was previously set to rprivate and didn't propagate
mounts from the host mount namespace into the daemon's mount namespace.

Further information about --propagation: https://github.com/rootless-containers/rootlesskit/tree/v0.9.1#mount-propagation
RootlessKit changes: https://github.com/rootless-containers/rootlesskit/compare/v0.8.0...v0.9.1

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

contrib/dockerd-rootless.sh

@@ -82,6 +82,7 @@ if [ -z $_DOCKERD_ROOTLESS_CHILD ]; then
 		--slirp4netns-seccomp=$DOCKERD_ROOTLESS_ROOTLESSKIT_SLIRP4NETNS_SECCOMP \
 		--disable-host-loopback --port-driver=builtin \
 		--copy-up=/etc --copy-up=/run \
+		--propagation=rslave \
 		$DOCKERD_ROOTLESS_ROOTLESSKIT_FLAGS \
 		$0 $@
 else

hack/dockerfile/install/rootlesskit.installer

@@ -1,7 +1,7 @@
 #!/bin/sh
 
-# v0.8.0
-: ${ROOTLESSKIT_COMMIT:=ce88a431e6a7cf891ebb68b10bfc6a5724b9ae72}
+# v0.9.1
+: ${ROOTLESSKIT_COMMIT:=db9657404cd538820e9e83d90dab2a78d8b833e6}
 
 install_rootlesskit() {
 	case "$1" in