Merge ~raharper/curtin:fix/vmtest-early-rsync-error into curtin:master

[Ryan Harper]

vmtest: rsync don't cross filesystem boundaries when copying

In some scenarios /var/lib/lxcfs is mounted with kernel bits
and rsync complains; instead we now copy using the --one-file-system
flag which avoids crossing these boundaries.

LP: #1873909

[Chad Smith (chad.smith)]

Looks like the right change to make for the failing test.
Can see how this goes w/ unittest vmtest run.

review: Approve

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:276120a349aaf847b303e1e544359aece7068ef8
https://jenkins.ubuntu.com/server/job/curtin-ci/53/
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    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-amd64/53/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-arm64/53/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-ppc64el/53/
    SUCCESS: https://jenkins.ubuntu.com/server/job/curtin-ci/nodes=metal-s390x/53/

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review: Approve (continuous-integration)

diff --git a/examples/tests/reuse-lvm-member-partition.yaml b/examples/tests/reuse-lvm-member-partition.yaml
index 8d025aa..d2f73ba 100644
--- a/examples/tests/reuse-lvm-member-partition.yaml
+++ b/examples/tests/reuse-lvm-member-partition.yaml
@@ -34,7 +34,7 @@ bucket:
     # populate the lv with data to ensure we allocate extents on both pv devs
     mkfs.ext4 /dev/${VG}/${LV}
     mount /dev/${VG}/${LV} /mnt
-    rsync -aqpP /var /mnt
+    rsync -aqpP --one-file-system /var /mnt
     umount /mnt
     # simulate the first boot environment by turning off the vg, and wiping
     # one physical volume